When building target binaries, ensure that the warning flags selected for the command...

When building target binaries, ensure that the warning flags selected for the command line match the target compiler.

bfd	* warning.m4 (AC_EGREP_CPP_FOR_BUILD): Introduce macro
	to verify CC_FOR_BUILD compiler.
	(AM_BINUTILS_WARNINGS): Introduce ac_cpp_for_build variable
	and add CC_FOR_BUILD compiler checks.
	* Makefile.in: Regenerate.
	* configure: Likewise.
	* doc/Makefile.in: Likewise.

binutils	* Makefile.am: Replace AM_CLFAGS with AM_CFLAGS_FOR_BUILD
	when building with CC_FOR_BUILD compiler.
	* Makefile.in: Regenerate.
	* configure: Likewise.
	* doc/Makefile.in: Likewise.

gas	* Makefile.in: Regenerate.
	* configure: Likewise.
	* doc/Makefile.in: Likewise.

gold	* Makefile.in: Regenerate.
	* configure: Likewise.
	* testsuite/Makefile.in: Likewise.

gprof	* Makefile.in: Regenerate.
	* configure: Likewise.

ld	* Makefile.in: Regenerate.
	* configure: Likewise.

opcodes	* Makefile.in: Regenerate.
	* configure: Likewise.