Fixed 64-bit ints in LZMA SDK on Watcom C.

src/physfs_lzmasdk.h

@@ -83,7 +83,7 @@ typedef unsigned long UInt64;
 
 #else
 
-#if defined(_MSC_VER) || defined(__BORLANDC__)
+#if defined(_MSC_VER) || defined(__BORLANDC__) || defined(__WATCOMC__)
 typedef __int64 Int64;
 typedef unsigned __int64 UInt64;
 #define UINT64_CONST(n) n