core: Insure "il" is initialized in all cases

Prior this commit, "il" was not initialized and check_int() was supposed
to setup it's value before usage.

In fact, check_int() can let "il" uninitialized leading to a dprint()
with a unintialized value.
diff --git a/parse.c b/parse.c
index f54dae6..d3eb2c4 100644
--- a/parse.c
+++ b/parse.c
@@ -380,7 +380,7 @@
 static int __handle_option(struct fio_option *o, const char *ptr, void *data,
 			   int first, int more, int curr)
 {
-	int il, *ilp;
+	int il=0, *ilp;
 	fio_fp64_t *flp;
 	long long ull, *ullp;
 	long ul1, ul2;