RandomX: added Blake2 AVX2 version

+0.1% speedup on AMD Zen2/Zen3 and Intel CPUs which support AVX2.

src/crypto/randomx/blake2/avx2/blake2.h

@@ -0,0 +1,38 @@
+#ifndef BLAKE2_AVX2_BLAKE2_H
+#define BLAKE2_AVX2_BLAKE2_H
+
+#if !defined(__cplusplus) && (!defined(__STDC_VERSION__) || __STDC_VERSION__ < 199901L)
+  #if   defined(_MSC_VER)
+    #define INLINE __inline
+  #elif defined(__GNUC__)
+    #define INLINE __inline__
+  #else
+    #define INLINE
+  #endif
+#else
+  #define INLINE inline
+#endif
+
+#if defined(_MSC_VER)
+#define ALIGN(x) __declspec(align(x))
+#else
+#define ALIGN(x) __attribute__((aligned(x)))
+#endif
+
+enum blake2s_constant {
+  BLAKE2S_BLOCKBYTES = 64,
+  BLAKE2S_OUTBYTES   = 32,
+  BLAKE2S_KEYBYTES   = 32,
+  BLAKE2S_SALTBYTES  = 8,
+  BLAKE2S_PERSONALBYTES = 8
+};
+
+enum blake2b_constant {
+  BLAKE2B_BLOCKBYTES = 128,
+  BLAKE2B_OUTBYTES   = 64,
+  BLAKE2B_KEYBYTES   = 64,
+  BLAKE2B_SALTBYTES  = 16,
+  BLAKE2B_PERSONALBYTES = 16
+};
+
+#endif