Code move src/ -> hphp/

This change is mostly for FB internal organizational reasons.
Building is not effected beyond the fact that the target now
lands in hphp/hhvm/hhvm rather than src/hhvm/hhvm.
Update third_party/folly
Add folly experimental components
Get rid of third-party XHP since it's actually part of the parser
Update folly
Add install target (and remove errant install targets from 3rd party)

make install
  Installs hhvm and systemlib.php to CMAKE_INSTALL_PREFIX/bin

To override the default location define it during cmake:
  cmake -DCMAKE_INSTALL_PREFIX=/usr/hphp .
Link dl, pthread, and glog into gen-ext-hhvm, gen-infotabs, and folly
Add missing macros to timelib_config.h

The absence of HAVE_LIMITS_H caused timelib_structs.h to define LONG_MIN
and LONG_MAX to be 32-bit values, which caused timelib_date_to_int() to
give an error for a date after 2038, which caused the current time to be
returned for e.g. date_create('28 July 2038')->format('r').

The issue was detected by MediaWiki unit tests, and this fix was tested
by the same method.

While I was at it, I also added HAVE_LOCALE_H, which was checked for in
CMakeLists.txt but not used, and I fixed the definition of SIZEOF_INT
(#cmakedefine doesn't work that way). I arranged the macros in
timelib_config.h.cmake in the same order as they are in CMakeLists.txt.
change AM_CONFIG_HEADER to AC_CONFIG_HEADERS

This is needed for OSX and I think fixes a spew on others
fix spew in folly (this is already upstream in folly)
Merge pull request #770 from ptarjan/fix_cmake_patch

Fix cmake patch
Update folly
Update folly
fix unused variables in third-party
Update Folly
Bundle libmbfl filter files by default

Unicode.org's license allows us to redistribute these files
so long as they contain their original notice, so let's do so
and remove the need to download the files on every new checkout.

To force-update any file, just delete it and the build script
will download the most current version from unicode.org
Update timelib and datetime functons to match
Update folly
Add EastAsianWidth.txt to checked in files
Update folly