grep: read -f file with strbuf_getline()

List of patterns file could come from a DOS editor.

This is iffy; you may actually be trying to find a line with ^M in
it on a system whose line ending is LF.  You can of course work it
around by having a line that has "^M^M^J", let the strbuf_getline()
eat the last "^M^J", leaving just the single "^M" as the pattern.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/grep.c

@@ -562,7 +562,7 @@ static int file_callback(const struct option *opt, const char *arg, int unset)
 	patterns = from_stdin ? stdin : fopen(arg, "r");
 	if (!patterns)
 		die_errno(_("cannot open '%s'"), arg);
-	while (strbuf_getline_lf(&sb, patterns) == 0) {
+	while (strbuf_getline(&sb, patterns) == 0) {
 		/* ignore empty line like grep does */
 		if (sb.len == 0)
 			continue;