Darwin does not support gsplit-dwarf.

Darwin does not support gsplit-dwarf.

2018-08-18  Iain Sandoe  <iain@sandoe.co.uk>

gcc/

	* config/darwin.c (darwin_override_options): If -gsplit-dwarf is set,
	emit a diagnostic that it is not supported and reset the option.
	* config/darwin.h (DRIVER_SELF_SPECS): Note that gsplit-dwarf is not
	supported and consume the option.  (ASM_FINAL_SPEC): New.

gcc/testsuite

	* g++.dg/debug/dwarf2/pr85302.C: Skip unsupported split DWARF
	test on Darwin.
	* g++.dg/debug/dwarf2/pr85302.C: Likewise.
	* gcc.dg/lto/pr83719_0.c: Likewise.

From-SVN: r263645