win32: Allow other programs to open the same files

In order to match Linux behaviour better our Windows-specific
open() replacement should disable Windows default file locking.
Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/os_support.c

@@ -32,6 +32,7 @@
 #include <fcntl.h>
 #include <io.h>
 #include <windows.h>
+#include <share.h>
 
 int ff_win32_open(const char *filename_utf8, int oflag, int pmode)
 {
@@ -46,12 +47,12 @@ int ff_win32_open(const char *filename_utf8, int oflag, int pmode)
     filename_w = av_mallocz(sizeof(wchar_t) * num_chars);
     MultiByteToWideChar(CP_UTF8, 0, filename_utf8, -1, filename_w, num_chars);
 
-    fd = _wopen(filename_w, oflag, pmode);
+    fd = _wsopen(filename_w, oflag, SH_DENYNO, pmode);
     av_freep(&filename_w);
 
     /* filename maybe be in CP_ACP */
     if (fd == -1 && !(oflag & O_CREAT))
-        return open(filename_utf8, oflag, pmode);
+        return _sopen(filename_utf8, oflag, SH_DENYNO, pmode);
 
     return fd;
 }