I80960XL support (sanitized), misc cleanup:

I80960XL support (sanitized), misc cleanup:

* config/tc-i960.h (TC_COFF_SET_MACHINE): New macro.  Calls tc_headers_hook.

* config/tc-i960.c (targ_has_iclass): Use I_CX | I_CX2 where I_CX was used
previously.
(tc_headers_hook): If I_CX2 is found, set flags to F_I960CA.

* config/tc-i960.c (po_hash): Declaration deleted.
(next_object_file_charP): Ditto.
(regnames, aregs, coj): Now const.
(parse_memop): Static array def_scale now const.
(md_begin): Cast away const when passing hash routines addresses of values in
regnames or aregs.
(md_longopts): Added "link-relax" and "no-relax" hyphenated forms.  Continue to
accept one-word forms.
(struct tabentry, arch_tab): Moved to top level from inside md_parse_option.
Now const.
(md_show_usage): Use arch_tab to generate usage message.  Print hyphenated
forms of relax options.

* config/tc-i960.h (DEFINE_I960_AOUT, TC_S_IS_*, TC_S_*_SYSPROC,
TC_S_FORCE_TO_*): Moved from here...
* config/tc-i960.c: ... to here.  Changed DEFINE_I960_AOUT stuff to test
OBJ_AOUT and OBJ_BOUT directly.

* config/tc-i960.h (CTRL, COBR, COJ, REG, MEM*, FBRA, CALLJ, M1-M3, REG_OPC,
R_*, SFR, LIT, FP, OP, R, RS, RL, RSL, F, {R,F}{,L}{2,4}, M, SFR_OK, LIT_OK,
FP_OK, REG_ALIGN, MEMOP, I_*): Macros deleted.

* config/tc-i960.c (ARCH_XL): Define.
(arch_tab): Include XL.
(targ_has_sfr, targ_has_iclass): Handle XL.
(tc_headers_hook): Set flags to F_I960XL for i960XL.