[Darwin, machopic 10/n] Rework X86 mcount stub code.

[Darwin, machopic 10/n] Rework X86 mcount stub code.

When a stub is used to call the mcount function, the code is already
marking it as used unconditionally;  This is the only use of the so-
called validation outside darwin.{h,c}.  This moves the 'validation'
into darwin.c which is a step towards making validation routine local.

gcc/

2019-11-09  Iain Sandoe  <iain@sandoe.co.uk>

	* config/darwin.c (machopic_mcount_stub_name): Validate the
	symbol stub name when it is created.
	* config/i386/darwin.h (FUNCTION_PROFILER): Remove the symbol
	stub validation.

From-SVN: r278000