tools: convert makefiles to kbuild style

Before this commit, makefiles under tools/ directory
were implemented with their own way.

This commit refactors them by using "hostprogs-y" variable.

Several C sources have been added to wrap other C sources
to simplify Makefile.
For example, tools/crc32.c includes lib/crc32.c

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/tools/easylogo/Makefile b/tools/easylogo/Makefile
index d8e28b0..10aba2b 100644
--- a/tools/easylogo/Makefile
+++ b/tools/easylogo/Makefile
@@ -1,11 +1,3 @@
-include $(TOPDIR)/config.mk
+hostprogs-y := easylogo
 
-all: $(obj)easylogo
-
-$(obj)easylogo: $(SRCTREE)/tools/easylogo/easylogo.c
-	$(HOSTCC) $(HOSTCFLAGS_NOPED) $(HOSTLDFLAGS) -o $@ $^
-
-clean:
-	rm -f $(obj)easylogo
-
-.PHONY: all clean
+always := $(hostprogs-y)