change how ffmsindex is linked to ffms2 (use a #pragma instead of an extra dependency in the project file)

Originally committed to SVN as r2902.

aegisub/FFmpegSource2/ffmsindex.cpp

@@ -24,6 +24,10 @@
 #include <stdlib.h>
 #include "ffms.h"
 
+#if _MSC_VER >= 1200
+#pragma comment(lib,"ffms2.lib")
+#endif /* _MSC_VER */
+
 int TrackMask;
 int DumpMask;
 bool Overwrite;