userdiff: support new keywords in PHP hunk header

Recent version of PHP supports interface, trait, abstract class and
final class.  This patch fixes the PHP hunk header regexp to support
all of these keywords.

Signed-off-by: Kana Natsuno <dev@whileimautomaton.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t4018/php-abstract-class

@@ -0,0 +1,4 @@
+abstract class RIGHT
+{
+    const FOO = 'ChangeMe';
+}

t/t4018/php-final-class

@@ -0,0 +1,4 @@
+final class RIGHT
+{
+    const FOO = 'ChangeMe';
+}

t/t4018/php-interface

@@ -0,0 +1,4 @@
+interface RIGHT
+{
+    public function foo($ChangeMe);
+}

t/t4018/php-trait

@@ -0,0 +1,7 @@
+trait RIGHT
+{
+    public function foo($ChangeMe)
+    {
+        return 'foo';
+    }
+}

userdiff.c

@@ -114,7 +114,7 @@ PATTERNS("perl",
 	 "|<<|<>|<=>|>>"),
 PATTERNS("php",
 	 "^[\t ]*(((public|protected|private|static)[\t ]+)*function.*)$\n"
-	 "^[\t ]*(class.*)$",
+	 "^[\t ]*((((final|abstract)[\t ]+)?class|interface|trait).*)$",
 	 /* -- */
 	 "[a-zA-Z_][a-zA-Z0-9_]*"
 	 "|[-+0-9.e]+|0[xXbB]?[0-9a-fA-F]+"