kbuild: get <linux/compiler_types.h> out of <linux/kconfig.h>

Since commit 28128c61e0 ("kconfig.h: Include compiler types to avoid
missed struct attributes"), <linux/kconfig.h> pulls in kernel-space
headers to unrelated places.

Commit 0f9da844d8 ("MIPS: boot: Define __ASSEMBLY__ for its.S build")
suppress the build error by defining __ASSEMBLY__, but ITS (i.e. DTS)
is not assembly, and should not include <linux/compiler_types.h> in the
first place.

Looking at arch/s390/tools/Makefile, host programs gen_facilities and
gen_opcode_table now pull in <linux/compiler_types.h> as well.

The motivation for that commit was to define necessary attributes
before any struct is defined.  Obviously, this happens only in C.

It is enough to include <linux/compiler_types.h> only when compiling
C files, and only when compiling kernel space.  Move the include to
c_flags.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

include/linux/kconfig.h

@@ -70,7 +70,4 @@
  */
 #define IS_ENABLED(option) __or(IS_BUILTIN(option), IS_MODULE(option))
 
-/* Make sure we always have all types and struct attributes defined. */
-#include <linux/compiler_types.h>
-
 #endif /* __LINUX_KCONFIG_H */

scripts/Makefile.lib

@@ -152,6 +152,7 @@ __cpp_flags     = $(call flags,_cpp_flags)
 endif
 
 c_flags        = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE)     \
+		 -include $(srctree)/include/linux/compiler_types.h       \
 		 $(__c_flags) $(modkern_cflags)                           \
 		 $(basename_flags) $(modname_flags)