rs6000: Add rs6000_cfun_pcrel_p

rs6000: Add rs6000_cfun_pcrel_p

Most uses of rs6000_pcrel_p are called for the current function.
A specialized version for cfun is more efficient for these uses.

2020-09-16  Bill Schmidt  <wschmidt@linux.ibm.com>

gcc/
	* config/rs6000/predicates.md (current_file_function_operand):
	Remove argument from rs6000_pcrel_p call.
	* config/rs6000/rs6000-logue.c (rs6000_decl_ok_for_sibcall):
	Likewise.
	(rs6000_global_entry_point_prologue_needed_p): Likewise.
	(rs6000_output_function_prologue): Likewise.
	* config/rs6000/rs6000-protos.h (rs6000_function_pcrel_p): New
	prototype.
	(rs6000_pcrel_p): Remove argument.
	* config/rs6000/rs6000.c (rs6000_legitimize_tls_address): Remove
	argument from rs6000_pcrel_p call.
	(rs6000_call_template_1): Likewise.
	(rs6000_indirect_call_template_1): Likewise.
	(rs6000_longcall_ref): Likewise.
	(rs6000_call_aix): Likewise.
	(rs6000_sibcall_aix): Likewise.
	(rs6000_function_pcrel_p): Rename from rs6000_pcrel_p.
	(rs6000_pcrel_p): Rewrite.
	* config/rs6000/rs6000.md (*pltseq_plt_pcrel<mode>): Remove
	argument from rs6000_pcrel_p call.
	(*call_local<mode>): Likewise.
	(*call_value_local<mode>): Likewise.
	(*call_nonlocal_aix<mode>): Likewise.
	(*call_value_nonlocal_aix<mode>): Likewise.
	(*call_indirect_pcrel<mode>): Likewise.
	(*call_value_indirect_pcrel<mode>): Likewise.