Move construction of IA-32 vector types to i386-tdep.c.

Move construction of IA-32 vector types to i386-tdep.c.
* gdbtypes.c (build_builtin_type_vec64i,
build_builtin_type_vec128i): Delete functions.
(builtin_type_vec64i, builtin_type_vec128i): Delete variables.
(build_gdbtypes): Don't initialize them.
(_initialize_gdbtypes): Don't register GDBARCH swap entries for
them.
* gdbtypes.h (builtin_type_vec64i, builtin_type_vec128i): Delete
declarations.
(builtin_type_v2_float, builtin_type_v2_int32,
builtin_type_v4_int16, builtin_type_v8_int8,
builtin_type_v2_double, builtin_type_v4_float,
builtin_type_v2_int64, builtin_type_v4_int32,
builtin_type_v8_int16, builtin_type_v16_int8): Add extern
declarations.
* i386-tdep.c (i386_mmx_type, i386_sse_type): New variables.
(i386_build_mmx_type, i386_build_sse_type): New functions.
(i386_register_type): Call them, rather than referring to
builtin_type_vec64i and builtin_type_vec128i.