MDL-55504 profiling: Support for PHPUnit and big profiles.

To support PHPUnit we need to support large profiles, these may
include backups and restores. To do that the following was required;
- gzcompress for database space saving.
- gzcompress for XML DomDocument field to say < 10Mb and allow imports.
- Save PHPUnit runs directly to a file so they can be imported to the normal database.
- Memory allowance on profiling view pages increases to support large profiles.

lib/phpunit/bootstrap.php

@@ -219,6 +219,10 @@ require_once("$CFG->dirroot/lib/phpunit/lib.php");
 
 // finish moodle init
 define('ABORT_AFTER_CONFIG_CANCEL', true);
+if (isset($CFG->phpunit_profilingenabled) && $CFG->phpunit_profilingenabled) {
+    $CFG->profilingenabled = true;
+    $CFG->profilingincluded = '*';
+}
 require("$CFG->dirroot/lib/setup.php");
 
 raise_memory_limit(MEMORY_HUGE);