Remove non-deterministic AVX APIs

Author: FeiPengIntel

src/mscorlib/src/System/Runtime/Intrinsics/X86/Avx.PlatformNotSupported.cs

@@ -1234,26 +1234,5 @@ public static class Avx
         ///   VXORPS ymm, ymm, ymm/m256
         /// </summary>
         public static Vector256<double> Xor(Vector256<double> left, Vector256<double> right) { throw new PlatformNotSupportedException(); }
-
-        /// <summary>
-        /// void _mm256_zeroall (void)
-        ///   VZEROALL
-        /// </summary>
-        public static void ZeroAll() { throw new PlatformNotSupportedException(); }
-        /// <summary>
-        /// void _mm256_zeroupper (void)
-        ///   VZEROUPPER
-        /// </summary>
-        public static void ZeroUpper() { throw new PlatformNotSupportedException(); }
-
-        /// <summary>
-        /// __m256d _mm256_zextpd128_pd256 (__m128d a)
-        ///   HELPER - No Codegen
-        /// __m256 _mm256_zextps128_ps256 (__m128 a)
-        ///   HELPER - No Codegen
-        /// __m256i _mm256_zextsi128_si256 (__m128i a)
-        ///   HELPER - No Codegen
-        /// </summary>
-        public static Vector256<T> ZeroExtendToVector256<T>(Vector128<T> value) where T : struct { throw new PlatformNotSupportedException(); }
     }
 }

src/mscorlib/src/System/Runtime/Intrinsics/X86/Avx.cs

@@ -1445,16 +1445,5 @@ public static bool TestZ<T>(Vector256<T> left, Vector256<T> right) where T : str
         ///   VXORPS ymm, ymm, ymm/m256
         /// </summary>
         public static Vector256<double> Xor(Vector256<double> left, Vector256<double> right) => Xor(left, right);
-
-        /// <summary>
-        /// void _mm256_zeroall (void)
-        ///   VZEROALL
-        /// </summary>
-        public static void ZeroAll() => ZeroAll();
-        /// <summary>
-        /// void _mm256_zeroupper (void)
-        ///   VZEROUPPER
-        /// </summary>
-        public static void ZeroUpper() => ZeroUpper();
     }
 }