Merge pull request #917 from rui314/missing-include

Add a missing #include

src/prim/unix/prim.c

@@ -27,6 +27,7 @@ terms of the MIT license. A copy of the license can be found in the file
 #include <sys/mman.h>  // mmap
 #include <unistd.h>    // sysconf
 #include <fcntl.h>     // open, close, read, access
+#include <stdlib.h>    // getenv, arc4random_buf
 
 #if defined(__linux__)
   #include <features.h>
@@ -780,7 +781,6 @@ bool _mi_prim_random_buf(void* buf, size_t buf_len) {
       defined(__sun) || \
       (defined(__APPLE__) && (MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_7))
 
-#include <stdlib.h>
 bool _mi_prim_random_buf(void* buf, size_t buf_len) {
   arc4random_buf(buf, buf_len);
   return true;