fdo#67534: try to avoid file locking in Explorer shell extensions

Change-Id: I287395f6c25b1bfb9b9482166ae6f34d9af8f455

shell/source/win32/shlxthandler/ooofilt/stream_helper.cxx

@@ -106,7 +106,8 @@ long BufferStream::sseek (long offset, int origin)
 FileStream::FileStream(const char *filename) :
     file(0)
 {
-    file = fopen(filename, "rb");
+    // fdo#67534: avoid locking to not interfere with soffice opening the file
+    file = _fsopen(filename, "rb", _SH_DENYNO);
 }
 
 FileStream::~FileStream()