Improved the Zend compatibility for ReflectionClass

Summary: `inNamespace()`, `getNamespaceName()`, and `getShortName()` should not be `final`. This was causing issues in phpspec which mocks these methods.

This was done for ReflectionFunctionAbstract in #3070 but ReflectionClass was missed

Closes #3233

Reviewed By: @ptarjan

Differential Revision: D1445618

hphp/runtime/ext/reflection/ext_reflection_hni.php

@@ -1323,7 +1323,7 @@ private function getParentName(): string;
    *
    * @return     bool   Returns TRUE on success or FALSE on failure.
    */
-  final public function inNamespace(): bool {
+  public function inNamespace(): bool {
     return strrpos($this->getName(), '\\') !== false;
   }
 
@@ -1335,7 +1335,7 @@ final public function inNamespace(): bool {
    *
    * @return     string   The namespace name.
    */
-  final public function getNamespaceName(): string {
+  public function getNamespaceName(): string {
     $name = $this->getName();
     $pos = strrpos($name, '\\');
     return ($pos === false) ? '' : substr($name, 0, $pos);
@@ -1349,7 +1349,7 @@ final public function getNamespaceName(): string {
    *
    * @return     string  The short name of the function.
    */
-  final public function getShortName(): string {
+  public function getShortName(): string {
     $name = $this->getName();
     $pos = strrpos($name, '\\');
     return ($pos === false) ? $name : substr($name, $pos + 1);