[Darwin, PPC] Use Darwin9 bundle header for Rosetta builds.

[Darwin, PPC] Use Darwin9 bundle header for Rosetta builds.

On Darwin10 it's possible to make a 32b PPC build using the
'Rosetta' emulator. However, these builds need to make use of
Darwin9 crts (for exes, dylibs and bundles). This adds the
change to cater for bundles.

gcc/ChangeLog:

	Backport from mainline.
	2019-12-14 Iain Sandoe <iain@sandoe.co.uk>

	* config/darwin.h (DARWIN_EXTRA_SPECS): Add new
	bundle spec. (DARWIN_BUNDLE1_SPEC): New.
	(STARTFILE_SPEC): Use darwin bundle spec.
	* config/rs6000/darwin.h (DARWIN_BUNDLE1_SPEC): New.
	(DARWIN_DYLIB1_SPEC): Delete duplicate.

From-SVN: r279732