fix appveyor build, us1.php.net is (currently?) unreachable

appveyor.yml

@@ -40,7 +40,7 @@ install:
   - curl -fSL -o %V8_ASSETS% "https://s3.amazonaws.com/win-phpv8/%V8_ASSETS%"
   - 7z.exe x %V8_ASSETS%
   - cd ..
-  - curl -fSL -o "php-%PHP_VERSION%.tar.gz" "http://us1.php.net/distributions/php-%PHP_VERSION%.tar.gz"
+  - curl -fSL -o "php-%PHP_VERSION%.tar.gz" "http://us2.php.net/distributions/php-%PHP_VERSION%.tar.gz"
   - ren php php-%PHP_VERSION%
   - 7z.exe x php-%PHP_VERSION%.tar.gz -y
   - 7z.exe x php-%PHP_VERSION%.tar -y | find /v "Extracting"