kbuild: use Linux Kernel build scripts

Now we are ready to switch over to real Kbuild.

This commit disables temporary scripts:
  scripts/{Makefile.build.tmp, Makefile.host.tmp}
and enables real Kbuild scripts:
  scripts/{Makefile.build,Makefile.host,Makefile.lib}.

This switch is triggered by the line in scripts/Kbuild.include
  -build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build.tmp obj
  +build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj

We need to adjust some build scripts for U-Boot.
But smaller amount of modification is preferable.

Additionally, we need to fix compiler flags which are
locally added or removed.

In Kbuild, it is not allowed to change CFLAGS locally.
Instead, ccflags-y, asflags-y, cppflags-y,
CFLAGS_$(basetarget).o, CFLAGS_REMOVE_$(basetarget).o
are prepared for that purpose.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Tested-by: Gerhard Sittig <gsi@denx.de>
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index ac780d4..e6d8be5 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -54,11 +54,11 @@
 # Workaround for local bus unaligned access problems
 # on MPC512x and MPC5200
 ifdef CONFIG_MPC512X
-$(obj)/ppcstring.o: AFLAGS += -Dmemcpy=__memcpy
+AFLAGS_ppcstring.o += -Dmemcpy=__memcpy
 obj-y += memcpy_mpc5200.o
 endif
 ifdef CONFIG_MPC5200
-$(obj)/ppcstring.o: AFLAGS += -Dmemcpy=__memcpy
+AFLAGS_ppcstring.o += -Dmemcpy=__memcpy
 obj-y += memcpy_mpc5200.o
 endif
 endif