libc should use O_CLOEXEC when opening files for its own use.

Change-Id: I159f1d57e0ca090d837f57854fcef5879b8b8248
diff --git a/libc/dns/resolv/res_init.c b/libc/dns/resolv/res_init.c
index f1cbed8..c05352a 100644
--- a/libc/dns/resolv/res_init.c
+++ b/libc/dns/resolv/res_init.c
@@ -289,7 +289,7 @@
 	 line[sizeof(name) - 1] == '\t'))
 
 	nserv = 0;
-	if ((fp = fopen(_PATH_RESCONF, "r")) != NULL) {
+	if ((fp = fopen(_PATH_RESCONF, "re")) != NULL) {
 	    /* read the config file */
 	    while (fgets(buf, sizeof(buf), fp) != NULL) {
 		/* skip comments */