mongodb 2.5.1

Closes #21293.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
mongodb: remove arch tag from version number
ohcount: update URLs

* Update the homepage to Github (http://git.io/Troz1g)
* Use the packaged source from GitHub
* Allow installation from HEAD

Closes #21257.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
mtr: add HEAD

Closes #21264.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
xctool 0.1.7

0.1.7 introduces a new directory layout where the xctool files are stored in
bin, lib, and libexec dirs -- https://github.com/facebook/xctool/commit/d6592a7

The old formula will probably break for anyone that tries to use --HEAD :-(

Closes #21199.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>