i386: Enable MMX intrinsics without SSE/SSE2/SSSE3

i386: Enable MMX intrinsics without SSE/SSE2/SSSE3

Since MMX intrinsics are marked with SSE/SSE2/SSSE3 for SSE emulation,
enable them without SSE/SSE2/SSSE3 if MMX is enabled.

Restore TARGET_3DNOW check, which was changed to TARGET_3DNOW_A by
revision 271235.

gcc/

	PR target/90497
	* config/i386/i386-expand.c (ix86_expand_builtin): Enable MMX
	intrinsics without SSE/SSE2/SSSE3.
	* config/i386/mmx.md (mmx_uavgv8qi3): Restore TARGET_3DNOW
	check.
	(*mmx_uavgv8qi3): Likewise.

gcc/testsuite/

	PR target/90497
	* gcc.target/i386/pr90497-1.c: New test.
	* gcc.target/i386/pr90497-2.c: Likewise.

From-SVN: r271328