Fix distcheck

Makefile.am

@@ -647,6 +647,7 @@ php_EXTRA_DIST=                                                       \
   php/src/Google/Protobuf/Internal/EnumBuilderContext.php             \
   php/src/Google/Protobuf/Internal/EnumDescriptor.php                 \
   php/src/Google/Protobuf/Internal/EnumDescriptorProto.php            \
+  php/src/Google/Protobuf/Internal/EnumDescriptorProto_EnumReservedRange.php \
   php/src/Google/Protobuf/Internal/EnumOptions.php                    \
   php/src/Google/Protobuf/Internal/EnumValueDescriptorProto.php       \
   php/src/Google/Protobuf/Internal/EnumValueOptions.php               \