(TARGET_SWITCHES): Add gas option.

(TARGET_SWITCHES): Add gas option.

(ASM_DECLARE_FUNCTION_NAME): Moved output of .ent directive to output_prolog.
(DBX_NO_XREFS): Removed, gdb understands cross references and the native
debugger can't handle embedded stabs.
(ASM_FILE_START): Replace output of .file directive by
ASM_OUTPUT_SOURCE_FILENAME call.
(TARGET_GAS, MASK_GAS, SDB_DEBUGGING_INFO, DBX_DEBUGGING_INFO,
MIPS_DEBUGGING_INFO, PREFERRED_DEBUGGING_TYPE, DEBUGGER_AUTO_OFFSET,
DEBUGGER_ARG_OFFSET, ASM_OUTPUT_SOURCE_LINE,
ASM_OUTPUT_SOURCE_FILENAME, DEFAULT_GDB_EXTENSIONS, ASM_STABS_OP,
ASM_STABN_OP, ASM_STABD_OP, SDB_ALLOW_FORWARD_REFERENCES,
SDB_ALLOW_UNKNOWN_REFERENCES, PUT_SDB_DEF, PUT_SDB_PLAIN_DEF,
PUT_SDB_TYPE, PUT_SDB_BLOCK_START, PUT_SDB_BLOCK_END,
PUT_SDB_FUNCTION_START, PUT_SDB_FUNCTION_END, PUT_SDB_EPILOGUE_END,
ASM_FINAL_SPEC, CODE_MASK, MIPS_IS_STAB, MIPS_MARK_STAB,
MIPS_UNMARK_STAB, SHASH_SIZE, THASH_SIZE): New macros.

From-SVN: r5760