file: Fallback to stat() based file_check() when access() or its named flags are unavailable.

Should fix compilation on native windows
We could also use _access() and literal numbers as flags but i cant test it
and the compilation failure should be fixed ASAP
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/file.c

@@ -85,6 +85,7 @@ static int file_get_handle(URLContext *h)
 
 static int file_check(URLContext *h, int mask)
 {
+#if defined(HAVE_ACCESS) && defined(R_OK)
     int ret = 0;
     if (access(h->filename, F_OK) < 0)
         return AVERROR(errno);
@@ -94,6 +95,15 @@ static int file_check(URLContext *h, int mask)
     if (mask&AVIO_FLAG_WRITE)
         if (access(h->filename, W_OK) >= 0)
             ret |= AVIO_FLAG_WRITE;
+#else
+    struct stat st;
+    int ret = stat(h->filename, &st);
+    if (ret < 0)
+        return AVERROR(errno);
+
+    ret |= st.st_mode&S_IRUSR ? mask&AVIO_FLAG_READ  : 0;
+    ret |= st.st_mode&S_IWUSR ? mask&AVIO_FLAG_WRITE : 0;
+#endif
     return ret;
 }