Fix build with gcc 4.8

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
[Upstream status: https://sourceforge.net/p/lgames/patches/28]
Index: ltris/src/bowl.c
===================================================================
--- ltris/src/bowl.c	(révision 421)
+++ ltris/src/bowl.c	(copie de travail)
@@ -828,9 +828,10 @@
 */
 void bowl_init_block_masks() 
 {
+	int i;
 	int masksize = sizeof(block_masks[0].mask); // same for all
 
-	for (int i = 0; i < 7; i++) {
+	for (i = 0; i < 7; i++) {
 		block_masks[i].rx = 2;
 		block_masks[i].ry = 2;
 		memset(block_masks[i].mask, 0, masksize );