Auto-generate luasandbox_version.h in config.cmake & config.m4

Have the build scripts for both PHP and HHVM automatically generate
luasandbox_version.h by parsing the version identifier from debian/changelog:
autoconf by invoking sed, and CMake using its native file IO and string
matching capabilities.

Also delete hhvm-cmake.patch, which is no longer needed now that HHVM supports
out-of-tree EZC builds.

Change-Id: Ieec77748522e0b5efd9bf6a24fb867c90b527d40