Move Darwin10 unwinder fix to a crt shim.

Move Darwin10 unwinder fix to a crt shim.

gcc/
	* config/darwin10.h (LINK_GCC_C_SEQUENCE_SPEC): Adjust to use the
	Darwin10-specific unwinder-shim.
	* config/darwin12.h (LINK_GCC_C_SEQUENCE_SPEC): Remove.
	* config/rs6000/darwin.h (DARWIN_CRT1_SPEC, DARWIN_DYLIB1_SPEC):
	New to cater for Darwin10 Rosetta.

libgcc/
	* config/unwind-dw2-fde-darwin.c
	(_darwin10_Unwind_FindEnclosingFunction): move from here ...
	* config/darwin10-unwind-find-enc-func.c: … to here.
	* config/t-darwin: Build Darwin10 unwinder shim crt.
	* libgcc/config.host: Add the Darwin10 unwinder shim.

From-SVN: r263765