disable php extension if php-config is missing

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@1004707 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/configure.ac b/configure.ac
index 0b0a095..dc08344 100644
--- a/configure.ac
+++ b/configure.ac
@@ -181,9 +181,12 @@
 AX_THRIFT_LIB(php_extension, [PHP_EXTENSION], yes)
 if test "$with_php_extension" = "yes"; then
   AC_PATH_PROG([PHP_CONFIG], [php-config])
-  AC_CONFIG_SUBDIRS([lib/php/src/ext/thrift_protocol])
+  if test -n "$PHP_CONFIG" ; then
+    AC_CONFIG_SUBDIRS([lib/php/src/ext/thrift_protocol])
+    have_php_extension="yes"
+  fi
 fi
-AM_CONDITIONAL(WITH_PHP_EXTENSION, [test -n "$PHP_CONFIG"])
+AM_CONDITIONAL(WITH_PHP_EXTENSION, [test "$have_php_extension" = "yes"])
 
 AX_THRIFT_LIB(ruby, [Ruby], yes)
 have_ruby=no
@@ -402,6 +405,10 @@
   echo
   echo "Using Python ................. : $PYTHON"
 fi
+if test "$have_php" = "yes" ; then
+  echo
+  echo "Using php-config ............. : $PHP_CONFIG"
+fi
 if test "$have_ruby" = "yes" ; then
   echo
   echo "Using Ruby ................... : $RUBY"