Darwin, config : Adjust X86 biarch definitions ordering [PR100269].

Darwin, config : Adjust X86 biarch definitions ordering [PR100269].

This reorganises the biarch definitions to cater for the
macro changes and removals at r12-36.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
PR target/100269 - [12 Regression] i686 biarch compiler fails for Darwin after r12-36.

        PR target/100269

gcc/ChangeLog:

	PR target/100269
	* config.gcc: Ensure that Darwin biarch definitions are
	added before i386.h.
	* config/i386/darwin.h (TARGET_64BIT): Remove.
	(PR80556_WORKAROUND): New.
	(REAL_LIBGCC_SPEC): Amend to use PR80556_WORKAROUND.
	(DARWIN_SUBARCH_SPEC): New.
	* config/i386/darwin32-biarch.h (TARGET_64BIT_DEFAULT,
	TARGET_BI_ARCH, PR80556_WORKAROUND): New.
	(REAL_LIBGCC_SPEC): Remove.
	* config/i386/darwin64-biarch.h (TARGET_64BIT_DEFAULT,
	TARGET_BI_ARCH, PR80556_WORKAROUND): New.
	(REAL_LIBGCC_SPEC): Remove.