The c-c++-common tests fail (or XPASS depending on which) on
powerpc Darwin because it doesn't currently emit .ident marker. 

Since there's no support for .ident in the assembler, we can't
enable the output and therefore these tests should be skipped.

2018-12-24  Iain Sandoe  <iain@sandoe.co.uk>

	* c-c++-common/ident-0a.c: Skip for powerpc-darwin.
	* c-c++-common/ident-0b.c: Likewise.
	* c-c++-common/ident-1a.c: Likewise.
	* c-c++-common/ident-1b.c: Likewise.
	* c-c++-common/ident-2a.c: Likewise.
	* c-c++-common/ident-2b.c: Likewise.

From-SVN: r267394