Use PHP built with --enable-sockets

Again, this flag was not seen in old versions, so it's unclear how
this functionality, per secondary report, was regressed.

Build instructions updated accordingly.

README.md

@@ -30,7 +30,7 @@ can be downloaded by the build pack (see the URIs in `compile`).
     # Affixed to all vendored binary output to represent changes to the
     # compilation environment without a change to the upstream version,
     # e.g. PHP 5.3.27 without, and then subsequently with, libmcrypt.
-    heroku_rev='-1'
+    heroku_rev='-2'
 
     # Clear /app directory
     find /app -mindepth 1 -print0 | xargs -0 rm -rf
@@ -101,7 +101,7 @@ can be downloaded by the build pack (see the URIs in `compile`).
     --with-mysql --with-pdo-mysql --with-pgsql --with-pdo-pgsql         \
     --with-iconv --with-gd --with-curl=/usr/lib                         \
     --with-config-file-path=/app/php --enable-soap=shared               \
-    --with-openssl --with-mcrypt=/app/vendor/mcrypt
+    --with-openssl --with-mcrypt=/app/vendor/mcrypt --enable-sockets
     make -s
     make install -s
     popd

bin/compile

@@ -9,7 +9,7 @@ set -e
 # Affixed to all vendored binary output to represent changes to the
 # compilation environment without a change to the upstream version,
 # e.g. PHP 5.3.27 without, and then subsequently with, libmcrypt.
-heroku_rev='-1'
+heroku_rev='-2'
 
 # config
 MCRYPT_VERSION="2.5.8"