Add Darwin (Mac OS X kernel) native support.

Add Darwin (Mac OS X kernel) native support.

        * config.gcc (powerpc-*-darwin*): Add native bits.
        * config/darwin.c: New file, generic Darwin support functions.
        * config/darwin.h: New file, generic Darwin definitions.
        * config/darwin-protos.h: New file, generic Darwin prototypes.
        * rs6000/darwin.h: New file, Darwin for PowerPC.
        * rs6000/t-darwin: New file, Darwin makefile fragment.
        * rs6000/rs6000.h (OBJECT_MACHO): New macro.
        (TARGET_MACHO): Ditto.
        (rs6000_abi): Add ABI_DARWIN.
        (RS6000_REG_SAVE): Add ABI_DARWIN case.
        (RS6000_SAVE_AREA): Ditto.
        (FP_ARG_MAX_REG): Ditto.
        (RETURN_ADDRESS_OFFSET): Ditto.
        * rs6000/rs6000.c (rs6000_legitimize_address): Add TARGET_MACHO
        cases.
        (rs6000_emit_move): Add ABI_DARWIN cases.
        (print_operand): Ditto.
        (first_reg_to_save): Ditto.
        (rs6000_stack_info): Ditto, also align stack by 16 instead of 8.
        (debug_stack_info): Ditto.
        (rs6000_emit_prologue): Ditto.
        (rs6000_emit_epilogue): Ditto.
        (output_profiler_hook): Ditto.
        (output_function_profiler): Ditto.
        (rs6000_add_gc_roots): Call machopic_add_gc_roots if TARGET_MACHO.
        (output_mi_thunk): Add TARGET_MACHO case.
        (add_compiler_stub): Ditto.
        (output_compiler_stub): Ditto.
        (no_previous_def): Ditto.
        (output_call): Ditto.
        (machopic_output_stub): Ditto.
        (rs6000_machopic_legitimize_pic_address): Ditto.
        (toc_section): Ditto.
        * rs6000/rs6000.md (addsi3_high): New TARGET_MACHO pattern.
        (macho_high): Ditto.
        (macho_low): Ditto.
        (movsi_low): Ditto.
        (load_macho_picbase): Ditto.
        (call): Add TARGET_MACHO case to modify function.
        (call_value): Ditto.
        (call_nonlocal_sysv): Add ABI_DARWIN case.
        (call_value_nonlocal_sysv): Ditto.
        * rs6000/rs6000-protos.h (rs6000_machopic_legitimize_pic_address):
        Add prototype.
        (machopic_output_stub): Ditto.
        * ginclude/stddef.h: Test _BSD_WCHAR_T_DEFINED_.

From-SVN: r41277