buildenv/1.2.x/osx: update OpenSSL recipe to build using Xcode.app-style build.
buildenv/1.2.x/osx: update OpenSSL recipe to build using Xcode.app-style build.

Previously the OpenSSL recipe required people to have
Apple's command line build tools installed.

Now OpenSSL builds on correctly on Yosemite installs where
only Xcode is installed (no CLI tools required).

ccpgames/mumble-releng,ccpgames/mumble-releng