Increase max. number of exit stub groups to correspond with -Omaxsnap.

src/lj_def.h

@@ -79,7 +79,7 @@ typedef unsigned int uintptr_t;
 /* JIT compiler limits. */
 #define LJ_MAX_JSLOTS	250		/* Max. # of stack slots for a trace. */
 #define LJ_MAX_PHI	32		/* Max. # of PHIs for a loop. */
-#define LJ_MAX_EXITSTUBGR	8	/* Max. # of exit stub groups. */
+#define LJ_MAX_EXITSTUBGR	16	/* Max. # of exit stub groups. */
 
 /* Various macros. */
 #ifndef UNUSED