Give length to getcwd()

git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@5254 d4fa192b-c00b-0410-8231-f00ffab90ce4

bin/varnishtest/vtc.c

@@ -657,7 +657,7 @@ main(int argc, char * const *argv)
 	AZ(mkdir(vtc_tmpdir, 0700));
 	macro_def(vltop, NULL, "tmpdir", vtc_tmpdir);
 
-	cwd = getcwd(NULL, 0);
+	cwd = getcwd(NULL, PATH_MAX);
 	bprintf(topbuild, "%s/%s", cwd, TOP_BUILDDIR);
 	macro_def(vltop, NULL, "topbuild", topbuild);