Fix MSVC warnings

moo/mooedit/mootextbtree.c

@@ -322,7 +322,7 @@ static void
 merge_nodes (BTNode *parent, guint first)
 {
     BTNode *node, *next;
-    int i;
+    guint i;
 
     g_assert (first + 1 < parent->n_children);
 

moo/moolua/lua/luaall.cpp

@@ -2,9 +2,11 @@
 * all.c -- Lua core, libraries and interpreter in a single file
 */
 
+#ifdef __GNUC__
 #pragma GCC diagnostic ignored "-Wimplicit-fallthrough"
 #pragma GCC diagnostic ignored "-Wsign-compare"
 #pragma GCC diagnostic ignored "-Wmisleading-indentation"
+#endif
 
 #define luaall_c