kbuild: add CONFIG_ prefix to USE_PRIVATE_LIBGCC

Before this commit, USE_PRIVATE_LIBGCC was defined in
arch-specific config.mk and referenced in
arch/$(ARCH)/lib/Makefile.

We are not happy about parsing config.mk again and again.
We have to keep the same behavior with a different way.

By adding "CONFIG_" prefix, this macro appears
in include/autoconf.mk, include/spl-autoconf.mk.
(And treating USE_PRIVATE_LIBGCC as CONFIG macro
is reasonable enough.)

Tegra SoC family defined USE_PRIVATE_LIBGCC as "yes"
in arch/arm/cpu/arm720t/tegra*/config.mk,
whereas did not define it in arch/arm/cpu/armv7/tegra*/config.mk.

It means Tegra enables PRIVATE_LIBGCC only for SPL.
We can describe the same behavior by adding

  #ifdef CONFIG_SPL_BUILD
  # define CONFIG_USE_PRIVATE_LIBGCC
  #endif

to include/configs/tegra-common.h.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Tom Warren <twarren@nvidia.com>
Cc: Simon Glass <sjg@chromium.org>
Acked-by: Stephen Warren <swarren@nvidia.com>
diff --git a/arch/arm/cpu/arm720t/tegra114/config.mk b/arch/arm/cpu/arm720t/tegra114/config.mk
deleted file mode 100644
index 7947b50..0000000
--- a/arch/arm/cpu/arm720t/tegra114/config.mk
+++ /dev/null
@@ -1,19 +0,0 @@
-#
-# Copyright (c) 2010-2013, NVIDIA CORPORATION.  All rights reserved.
-#
-# (C) Copyright 2002
-# Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
-#
-# This program is free software; you can redistribute it and/or modify it
-# under the terms and conditions of the GNU General Public License,
-# version 2, as published by the Free Software Foundation.
-#
-# This program is distributed in the hope it will be useful, but WITHOUT
-# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
-# more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
-#
-USE_PRIVATE_LIBGCC = yes
diff --git a/arch/arm/cpu/arm720t/tegra124/config.mk b/arch/arm/cpu/arm720t/tegra124/config.mk
deleted file mode 100644
index 5e10701..0000000
--- a/arch/arm/cpu/arm720t/tegra124/config.mk
+++ /dev/null
@@ -1,7 +0,0 @@
-#
-# (C) Copyright 2010-2013
-# NVIDIA Corporation <www.nvidia.com>
-#
-# SPDX-License-Identifier:     GPL-2.0+
-#/
-USE_PRIVATE_LIBGCC = yes
diff --git a/arch/arm/cpu/arm720t/tegra20/config.mk b/arch/arm/cpu/arm720t/tegra20/config.mk
deleted file mode 100644
index e073345..0000000
--- a/arch/arm/cpu/arm720t/tegra20/config.mk
+++ /dev/null
@@ -1,10 +0,0 @@
-#
-# (C) Copyright 2010,2011
-# NVIDIA Corporation <www.nvidia.com>
-#
-# (C) Copyright 2002
-# Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
-#
-# SPDX-License-Identifier:	GPL-2.0+
-#
-USE_PRIVATE_LIBGCC = yes
diff --git a/arch/arm/cpu/arm720t/tegra30/config.mk b/arch/arm/cpu/arm720t/tegra30/config.mk
deleted file mode 100644
index 2388c56..0000000
--- a/arch/arm/cpu/arm720t/tegra30/config.mk
+++ /dev/null
@@ -1,19 +0,0 @@
-#
-# Copyright (c) 2010-2012, NVIDIA CORPORATION.  All rights reserved.
-#
-# (C) Copyright 2002
-# Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
-#
-# This program is free software; you can redistribute it and/or modify it
-# under the terms and conditions of the GNU General Public License,
-# version 2, as published by the Free Software Foundation.
-#
-# This program is distributed in the hope it will be useful, but WITHOUT
-# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
-# more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
-#
-USE_PRIVATE_LIBGCC = yes
diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile
index 45febcf..9fc81cd 100644
--- a/arch/arm/lib/Makefile
+++ b/arch/arm/lib/Makefile
@@ -5,17 +5,8 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-# Build private libgcc only when asked for
-ifdef USE_PRIVATE_LIBGCC
-lib-y	+= _ashldi3.o
-lib-y	+= _ashrdi3.o
-lib-y	+= _divsi3.o
-lib-y	+= _lshrdi3.o
-lib-y	+= _modsi3.o
-lib-y	+= _udivsi3.o
-lib-y	+= _umodsi3.o
-lib-y	+= div0.o
-endif
+lib-$(CONFIG_USE_PRIVATE_LIBGCC) += _ashldi3.o _ashrdi3.o _divsi3.o \
+			_lshrdi3.o _modsi3.o _udivsi3.o _umodsi3.o div0.o
 
 ifdef CONFIG_ARM64
 obj-y	+= crt0_64.o
diff --git a/arch/mips/lib/Makefile b/arch/mips/lib/Makefile
index 3705926..fabeb83 100644
--- a/arch/mips/lib/Makefile
+++ b/arch/mips/lib/Makefile
@@ -8,9 +8,4 @@
 obj-y	+= board.o
 obj-$(CONFIG_CMD_BOOTM) += bootm.o
 
-# Build private libgcc only when asked for
-ifdef USE_PRIVATE_LIBGCC
-lib-y	+= ashldi3.o
-lib-y	+= ashrdi3.o
-lib-y	+= lshrdi3.o
-endif
+lib-$(CONFIG_USE_PRIVATE_LIBGCC) += ashldi3.o ashrdi3.o lshrdi3.o
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index e6d8be5..0f62982 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -7,11 +7,7 @@
 
 ## Build a couple of necessary functions into a private libgcc
 ## if the user asked for it
-ifdef USE_PRIVATE_LIBGCC
-lib-y	+= _ashldi3.o
-lib-y	+= _ashrdi3.o
-lib-y	+= _lshrdi3.o
-endif
+lib-$(CONFIG_USE_PRIVATE_LIBGCC) += _ashldi3.o _ashrdi3.o _lshrdi3.o
 
 MINIMAL=
 
diff --git a/arch/sh/lib/Makefile b/arch/sh/lib/Makefile
index 5fc9d9d..8a84b24 100644
--- a/arch/sh/lib/Makefile
+++ b/arch/sh/lib/Makefile
@@ -15,15 +15,5 @@
 endif
 obj-$(CONFIG_CMD_SH_ZIMAGEBOOT) += zimageboot.o
 
-
-
-# Build private libgcc only when asked for
-ifdef USE_PRIVATE_LIBGCC
-lib-y	+= ashiftrt.o
-lib-y	+= ashiftlt.o
-lib-y	+= lshiftrt.o
-lib-y	+= ashldi3.o
-lib-y	+= ashrsi3.o
-lib-y	+= lshrdi3.o
-lib-y	+= movmem.o
-endif
+lib-$(CONFIG_USE_PRIVATE_LIBGCC) += ashiftrt.o ashiftlt.o lshiftrt.o \
+				    ashldi3.o ashrsi3.o lshrdi3.o movmem.o
diff --git a/arch/x86/config.mk b/arch/x86/config.mk
index 58dff14..1e52a5e 100644
--- a/arch/x86/config.mk
+++ b/arch/x86/config.mk
@@ -31,4 +31,4 @@
 export NORMAL_LIBGCC = $(shell $(CC) $(CFLAGS) -print-libgcc-file-name)
 PREFIXED_LIBGCC = $(OBJTREE)/arch/$(ARCH)/lib/$(shell basename $(NORMAL_LIBGCC))
 
-export USE_PRIVATE_LIBGCC=$(shell dirname $(PREFIXED_LIBGCC))
+CONFIG_USE_PRIVATE_LIBGCC=$(shell dirname $(PREFIXED_LIBGCC))