Fix _mm512_cvt_roundps_ph to generate sae instruction.

Fix _mm512_cvt_roundps_ph to generate sae instruction.

zmm-version vcvtps2ph is special, it encodes {sae} in evex, but put
round control in the imm. For intrinsic _mm512_cvt_roundps_ph (a,
imm), imm contains both {sae} and round control, we need to separate
it in the assembly output since vcvtps2ph will ignore imm[3:7].

gcc/ChangeLog:

	* config/i386/i386-builtin.def (IX86_BUILTIN_CVTPS2PH512):
	Map to CODE_FOR_avx512f_vcvtps2ph512_mask_sae.
	* config/i386/sse.md (<mask_codefor>avx512f_vcvtps2ph512<mask_name>): Extend to ..
	(<mask_codefor>avx512f_vcvtps2ph512<mask_name><round_saeonly_name>): .. this.
	(avx512f_vcvtps2ph512_mask_sae): New expander

gcc/testsuite/ChangeLog:

	* gcc.target/i386/avx512f-vcvtps2ph-sae.c: New test.