Bug 1035087 - Avoid recursing some "binaries" targets when recursing for "libs". r=gps
Bug 1035096 - Make mach environment --format=configure only display configure arguments if COMM_BUILD is not set in the environment. r=gps

Also cleanup the output logic so that the configure arguments header is not
displayed when there aren't configure arguments, and so that variables are
still displayed when there aren't configure arguments.
Bug 1035099 - Remove the comm-central workarounds from MozbuildObject.from_environment. r=gps