osmo_strlcpy: Clarify length calculation

Change-Id: I78dc7b87d5b42595c0b1392fce61606eae8f6ec8
diff --git a/src/utils.c b/src/utils.c
index 168f85f..772b671 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -576,7 +576,7 @@
 	size_t ret = src ? strlen(src) : 0;
 
 	if (siz) {
-		size_t len = (ret >= siz) ? siz - 1 : ret;
+		size_t len = OSMO_MIN(siz - 1, ret);
 		if (len)
 			memcpy(dst, src, len);
 		dst[len] = '\0';