tools: Fix mkimage build on FreeBSD 10.1

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

SVN-Revision: 44280

tools/mkimage/patches/100-freebsd-compat.patch

+--- a/Makefile
++++ b/Makefile
+@@ -584,7 +584,10 @@ UBOOTINCLUDE    := \
+ 		-I$(srctree)/arch/$(ARCH)/include \
+ 		-include $(srctree)/include/linux/kconfig.h
+ 
+-NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
++ifneq ($(shell uname),FreeBSD)
++  NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
++endif
++
+ CHECKFLAGS     += $(NOSTDINC_FLAGS)
+ 
+ # FIX ME