osmo-config-merge: fclose() what we fopen()

Change-Id: Ib44f902e5bca2277f1b340d34fabbd2a298d683e
Fixes: Coverity CID#188851
diff --git a/utils/osmo-config-merge.c b/utils/osmo-config-merge.c
index a872d64..afaf86b 100644
--- a/utils/osmo-config-merge.c
+++ b/utils/osmo-config-merge.c
@@ -144,6 +144,7 @@
 			if (indent > cur_indent+1) {
 				fprintf(stderr, "File '%s' isn't well-formed in line %u, aborting!\n",
 					fname, line_num);
+				fclose(infile);
 				return NULL;
 			}
 			/* new child to last node */
@@ -166,6 +167,7 @@
 		cur_indent = indent;
 	}
 
+	fclose(infile);
 	return root;
 }