re PR target/56347 (FAIL: gfortran.dg/integer_exponentiation_2.f90 -O2 execution test)

	PR target/56347
	* config/pa/pa.md (call_value): Check for calls to powf and direct to
	new call patterns that clobber %fr12.
	(call_val_powf, call_val_powf_pic, call_val_powf_64bit): New insn,
	split and postreload patterns.
	* config/pa/pa.c (pa_conditional_register_usage): Revert marking
	registers %fr12 and %fr12R as call used.

From-SVN: r196588