Fix compilation on Linux, add error checking to Win32 SCFmemopen and properly indent.

src/util-fmemopen.c

@@ -5,14 +5,8 @@
  *         Based on FMem.c of Alexandre Flori (2008/10/17 AF)
  */
 
-#define _GNU_SOURCE
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include "util-fmemopen.h"
-
 #include "suricata-common.h"
+#include "util-fmemopen.h"
 
 #ifdef OS_DARWIN
 #define USE_FMEM_WRAPPER 1
@@ -43,6 +37,9 @@ FILE *SCFmemopen(void *buf, size_t size, const char *mode) {
         return NULL;
 
     FILE *f = fopen(filename, "wb");
+    if (NULL == f)
+        return NULL;
+
     fwrite(buf, size, 1, f);
     fclose(f);