add agetline, separate estrtod to util

Signed-off-by: Hiltjo Posthuma <hiltjo@codemadness.org>

util/agetline.c

@@ -0,0 +1,13 @@
+/* See LICENSE file for copyright and license details. */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "../text.h"
+#include "../util.h"
+
+ssize_t
+agetline(char **p, size_t *size, FILE *fp)
+{
+	return getline(p, size, fp);
+}