libgcc, rs6000: Remove powerpcspe related code

Since r9-4728 the powerpcspe support had been removed, this
follow-up patch is to remove the remaining pieces in libgcc.

libgcc/ChangeLog:

	* config.host: Remove powerpc-*-eabispe* support.
	* config/rs6000/linux-unwind.h (ppc_fallback_frame_state): Remove
	__SPE__ code.
	* config/rs6000/t-savresfgpr (LIB2ADD_ST): Remove e500crtres32gpr.S,
	e500crtres32gpr.S, e500crtsav64gpr.S, e500crtsav64gprctr.S,
	e500crtres64gpr.S, e500crtsav32gpr.S, e500crtsavg32gpr.S,
	e500crtres64gprctr.S, e500crtsavg64gprctr.S, e500crtresx32gpr.S,
	e500crtrest32gpr.S, e500crtrest64gpr.S and e500crtresx64gpr.S.
	* config/rs6000/e500crtres32gpr.S: Remove.
	* config/rs6000/e500crtres64gpr.S: Remove.
	* config/rs6000/e500crtres64gprctr.S: Remove.
	* config/rs6000/e500crtrest32gpr.S: Remove.
	* config/rs6000/e500crtrest64gpr.S: Remove.
	* config/rs6000/e500crtresx32gpr.S: Remove.
	* config/rs6000/e500crtresx64gpr.S: Remove.
	* config/rs6000/e500crtsav32gpr.S: Remove.
	* config/rs6000/e500crtsav64gpr.S: Remove.
	* config/rs6000/e500crtsav64gprctr.S: Remove.
	* config/rs6000/e500crtsavg32gpr.S: Remove.
	* config/rs6000/e500crtsavg64gpr.S: Remove.
	* config/rs6000/e500crtsavg64gprctr.S: Remove.