Fix CMake whitespace

Applied a two-space indent. It was a mixture of 2, 3, 4 and 8 space
indents and tabs; I don't know how you could look at it without going
crazy. I mostly used Vim's "=" command, even in cases where its output
is potentially controversial, because at least it's consistent.

Also modified vertical whitespace in a couple of places. A
whitespace-insensitive diff will show you where.

Fixed DOS line endings in FindBISON.cmake, which were reported by git as
whitespace errors.
EZC: allow dynamically loadable Zend compat extensions

* Use the existing macro ZEND_GET_MODULE() to provide the necessary
  getModule() function.
* In CMake, add macro HHVM_COMPAT_EXTENSION(), equivalent to
  HHVM_EXTENSION(), which will register a zend-compat extension.
* Set the source language, so that it's not even necessary to rename the
  files. This makes it trivial to have a dual-targeted source tree.