i386: Make __builtin_ia32_f{nstenv,ldenv,nstsw,fnclex} builtins internal [PR117165]

As the comment says, these builtins are meant to be internal for the atomic
support and cause various ICEs when using them directly in various
conditions.
So the following patch makes them internal.
We do have also internal-fn.*, but those target specific builtins would
need to be there in generic code, so I've just added space to their name,
which is the old way to hide builtins/attributes etc.

2024-11-22  Jakub Jelinek  <jakub@redhat.com>

	PR target/117165
	* config/i386/i386-builtin.def (IX86_BUILTIN_FNSTENV,
	IX86_BUILTIN_FLDENV, IX86_BUILTIN_FNSTSW, IX86_BUILTIN_FNCLEX): Add
	space to the end of the builtin name to make it really internal.

	* gcc.target/i386/pr117165.c: New test.