Updated mockery to 0.9.2

Summary: There is one issue here:

```
1) Mockery\Generator\MockConfigurationBuilderTest::reservedWordsAreBlackListedByDefault

RUN TEST FILE:  cd /root/hhvm/hphp/test/frameworks/framework_downloads/mockery && /root/hhvm/hphp/test/frameworks/../../hhvm/hhvm -v Repo.Local.Mode=-- -v Repo.Central.Path=/tmp/framework-testgHoUxi --config /root/hhvm/hphp/test/frameworks/php.ini -c /root/hhvm/hphp/test/frameworks/framework_class_overrides/Mockery.ini /root/hhvm/hphp/test/frameworks/framework_class_overrides/../vendor/bin/phpunit --debug  -c /root/hhvm/hphp/test/frameworks/framework_downloads/mockery/phpunit.xml.dist --filter 'Mockery\\Generator\\MockConfigurationBuilderTest::reservedWordsAreBlackListedByDefault'

Need a builtin class with a method that is a reserved word

/root/hhvm/hphp/test/frameworks/framework_downloads/mockery/tests/Mockery/Test/Generator/MockConfigurationBuilderTest.php:19
/root/hhvm/hphp/test/frameworks/vendor/phpunit/phpunit/src/TextUI/Command.php:186
/root/hhvm/hphp/test/frameworks/vendor
Closes https://github.com/facebook/hhvm/pull/3676

Reviewed By: @fredemmott, @JoelMarcey

Differential Revision: D1539922