php: disable a bunch of stuff for builds we don't need extensions for

This should speed up the build for a few minutes and hopefully won't
break anything
atom: $RPM_BUILD_ROOT => %{buildroot}
atom: bump to 0.115.0

Changes:

* Bump Atom to new upstream release 0.115.0
* Alter the way we link binaries onto $PATH -- perform linking at
  build time, not install time, and package the links
* Correctly install launcher for the application