THRIFT-4975: Add Makefile.am to the PHP tutorial

Client: php

This closes #1900.
diff --git a/tutorial/Makefile.am b/tutorial/Makefile.am
index 9160ad0..49d18fb 100755
--- a/tutorial/Makefile.am
+++ b/tutorial/Makefile.am
@@ -87,6 +87,10 @@
 SUBDIRS += perl
 endif
 
+if WITH_PHP
+SUBDIRS += php
+endif
+
 #
 # generate html for ThriftTest.thrift
 #
@@ -108,7 +112,6 @@
 	erl \
 	hs \
 	ocaml \
-	php \
 	shared.thrift \
 	tutorial.thrift \
 	README.md