re PR target/55712 (cpuinfo.c doesn't compile for x86-64 with medium memory model)

re PR target/55712 (cpuinfo.c doesn't compile for x86-64 with medium memory model)

	PR target/55712
	* config/i386/i386-c.c (ix86_target_macros_internal): Depending on
	selected code model, define __code_mode_small__, __code_model_medium__,
	__code_model_large__, __code_model_32__ or __code_model_kernel__.
	* config/i386/cpuid.h (__cpuid, __cpuid_count) [__i386__]: Prefix
	xchg temporary register with %k.  Declare temporary register as
	early clobbered.
	[__x86_64__]: For medium and large code models, preserve %rbx register.

From-SVN: r194862