Properly create xhpast database

Summary:
It isn't deleted by `storage destroy`.

This should be a no-op on current storage because we execute `CREATE DATABASE IF NOT EXISTS`.

Test Plan:
  $ bin/storage destroy --dryrun

Reviewers: nh, epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D3659

resources/sql/patches/xhprof.sql

@@ -1,4 +1,3 @@
-CREATE DATABASE {$NAMESPACE}_xhprof;
 CREATE TABLE {$NAMESPACE}_xhprof.xhprof_sample (
   `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
   `filePHID` VARCHAR(64) NOT NULL COLLATE utf8_bin,