Don't symlink PHPUnit uninstall XML config

It doesn't appear to work properly on PHP 5.2, giving the error:

```
Fatal error: Uncaught exception 'PHPUnit_Framework_Exception' with message 'Neither ".php" nor ".php" could be opened.' in /home/travis/.phpenv/versions/5.2.17/pear/PHPUnit/Util/Skeleton/Test.php:100

Stack trace:
#0 /home/travis/.phpenv/versions/5.2.17/pear/PHPUnit/TextUI/Command.php(157): PHPUnit_Util_Skeleton_Test->__construct('', '')
#1 /home/travis/.phpenv/versions/5.2.17/pear/PHPUnit/TextUI/Command.php(130): PHPUnit_TextUI_Command->run(Array, true)
#2 /home/travis/.phpenv/versions/5.2.17/bin/phpunit(46): PHPUnit_TextUI_Command::main()
#3 {main}
  thrown in /home/travis/.phpenv/versions/5.2.17/pear/PHPUnit/Util/Skeleton/Test.php on line 100
 ```

phpunit.uninstall.xml.dist

@@ -0,0 +1,16 @@
+<phpunit
+		bootstrap="dev-lib/phpunit/module-bootstrap.php"
+		backupGlobals="false"
+		colors="true"
+	>
+	<testsuites>
+		<testsuite>
+			<file>tests/phpunit/test-uninstall.php</file>
+		</testsuite>
+	</testsuites>
+	<filter>
+		<whitelist>
+			<directory suffix=".php">src/</directory>
+		</whitelist>
+	</filter>
+</phpunit>