Explicitly create stack for compiled regexps

Summary: PMA_Operations_Test::testGetHtmlForCopyDatabase
PMA_Operations_Test::testGetHtmlForPartitionMaintenance
Closes https://github.com/facebook/hhvm/pull/4239

Reviewed By: @paulbiss

Differential Revision: D1679090

Signature: t1:1679090:1416463904:898d4d7200b2d809241484c6c92965485ed26627
Raise warning when put_contents on non-regular file with exclusive lock.

Summary: In file_put_contents(), raise warning if attempting to add an exclusive lock on non-regular file.

Passing vfsstream's filePutContentsLockShouldReportError test case.
Closes https://github.com/facebook/hhvm/pull/4238

Reviewed By: @paulbiss

Differential Revision: D1678644

Signature: t1:1678644:1416464069:78ae002251c6b6aa966520daef0d4b924f9e8b59