c-common.c: Move format checking code to ...

c-common.c: Move format checking code to ...

	* c-common.c: Move format checking code to ...
	* c-format.c: ... here.  New file.  Reorder some functions and
	declarations.
	(decl_handle_format_attribute, decl_handle_format_arg_attribute):
	New functions.
	* c-common.h (decl_handle_format_attribute,
	decl_handle_format_arg_attribute): Declare.
	* Makefile.in (C_AND_OBJC_OBJS): Add c-format.o.
	(c-common.o): Adjust dependencies.
	(c-format.o): New list of dependencies.

cp:
	* Make-lang.in (CXX_C_OBJS): Add c-format.o.

From-SVN: r38998