ggml : add support for the RISCV architecture (#1616)

Author: apcameron

ggml.c

@@ -186,10 +186,12 @@ typedef double ggml_float;
 #if defined(_MSC_VER) || defined(__MINGW32__)
 #include <intrin.h>
 #else
+#if !defined(__riscv)
 #include <immintrin.h>
 #endif
 #endif
 #endif
+#endif
 
 #ifdef __F16C__