config changes for musl libc support

config changes for musl libc support

On behalf of Szabolcs.Nagy@arm.com

2015-04-22  Gregor Richards  <gregor.richards@uwaterloo.ca>

	* config.gcc (LIBC_MUSL): New tm_defines macro.
	* config/linux.h (OPTION_MUSL): Define.
	(INCLUDE_DEFAULTS_MUSL_GPP, INCLUDE_DEFAULTS_MUSL_LOCAL,)
	(INCLUDE_DEFAULTS_MUSL_PREFIX, INCLUDE_DEFAULTS_MUSL_CROSS,)
	(INCLUDE_DEFAULTS_MUSL_TOOL, INCLUDE_DEFAULTS_MUSL_NATIVE): Define.

	* config/linux.opt (mmusl): New option.
	* configure.ac (gcc_cv_libc_provides_ssp): Add *-*-musl*.
	(gcc_cv_target_dl_iterate_phdr): Add *-linux-musl*.

	* configure: Regenerate.

From-SVN: r222326