i386: Reject -m96bit-long-double for 64bit targets [PR100041]

i386: Reject -m96bit-long-double for 64bit targets [PR100041]

64bit targets default to 128bit long double, so -m96bit-long-double should
not be used.  Together with -m128bit-long-double, this option was intended
to be an optimization for 32bit targets only.

Error out when -m96bit-long-double is used with 64bit targets.

2021-04-23  Uroš Bizjak  <ubizjak@gmail.com>

gcc/
	PR target/100041
	* config/i386/i386-options.c (ix86_option_override_internal):
	Error out when -m96bit-long-double is used with 64bit targets.
	* config/i386/i386.md (*pushxf_rounded): Remove pattern.

gcc/testsuite/

	PR target/100041
	* gcc.target/i386/pr79514.c (dg-error):
	Expect error for 64bit targets.