Fix test for EOF on continuation line

getline() returns -1 on EOF, need to not loose that by forcing
result to size_t (unsigned).

Reported-by: Petr Sabata
diff --git a/lib/utils.c b/lib/utils.c
index 1b42222..efaf377 100644
--- a/lib/utils.c
+++ b/lib/utils.c
@@ -700,7 +700,7 @@
 	while ((cp = strstr(*linep, "\\\n")) != NULL) {
 		char *line1 = NULL;
 		size_t len1 = 0;
-		size_t cc1;
+		ssize_t cc1;
 
 		if ((cc1 = getline(&line1, &len1, in)) < 0) {
 			fprintf(stderr, "Missing continuation line\n");