PR gdb/921

	PR gdb/921
	PR gdb/1646
	PR gdb/2175
	PR gdb/2176

	* Makefile.def (flags_to_pass): Add CPPFLAGS_FOR_BUILD and CPPFLAGS.
	* Makefile.tpl (BUILD_EXPORTS): Set CPPFLAGS.
	(EXTRA_BUILD_FLAGS): Correct typo.  Pass CPPFLAGS.
	(HOST_EXPORTS): Pass CPPFLAGS.
	(CPPFLAGS_FOR_BUILD, CPPFLAGS, CPPFLAGS_FOR_TARGET): Define.
	(LDFLAGS_FOR_TARGET): Initialize from configure script.
	(EXTRA_TARGET_FLAGS): Set CPPFLAGS.
	* Makefile.in, configure: Regenerated.
	* configure.ac: Set CPPFLAGS_FOR_TARGET, LDFLAGS_FOR_TARGET,
	and CPPFLAGS_FOR_BUILD.

	libiberty/
	* Makefile.in (CPPFLAGS): Define.
	(FLAGS_TO_PASS, COMPILE.c): Add CPPFLAGS.