Avoid generating RTL code when d->testing_p.

gcc/ChangeLog:

	PR target/112393
	* config/i386/i386-expand.cc (ix86_expand_vec_perm_vpermt2):
	Avoid generating RTL code when d->testing_p.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/pr112393.c: New test.