* config/i386/i386.c (isa_opts): Remove -m64.
(ix86_target_string): Properly handle -m32/-m64/-mx32.
(ix86_option_override_internal): Properly
set OPTION_MASK_ISA_64BIT and OPTION_MASK_ISA_X32 as well as
handle -m32, -m64 and -mx32.
* config/i386/i386.h (TARGET_X32): Replace OPTION_ISA_X32
with OPTION_ABI_X32. Moved after TARGET_LP64.
(TARGET_LP64): Changed to OPTION_ABI_64.
* config/i386/i386.opt (m64): Replace ISA_64BIT with ABI_64.
(mx32): Replace ISA_X32 with ABI_X32.