Remove hphpc support and deprecate related functions

hphpc has been superseded by hhvm, so support for hphpc is no longer
needed.

* Continue to use Preprocessor_Hash under HipHop since it is still
  faster under hhvm
* Keep $wgCompiledFiles for now, so that wikihiero doesn't give an error
  before Ic9d1e795 is merged
* Migrate the run-server script and associated configuration file to
  hhvm. Enable EnableStaticContentFromDisk since it doesn't seem
  ridiculously inefficient at first glance. Run from $IP rather than
  $IP/.. since hhvm is apparently not picky about sourcing files from
  outside of the current directory.

Change-Id: Ic3e769f1fbad4f7ad26dd819406796fee48c6b45
Merge "Remove hphpc support and deprecate related functions"