Bug 1094033 part 1 - Consolidate how to add new tiers. r=gps
Bug 1094033 part 2 - Add a "misc" parallel tier where to move parts of the libs tier that can be moved. r=gps
Bug 1094037 - Move EXTRA_COMPONENTS and EXTRA_PP_COMPONENTS to the misc tier. r=gps
Bug 1094080 - Add missing m4 quoting in MOZ_RUN_ALL_SUBCONFIGURES. r=mshal
Bug 1093499 - Add a -C option to mach build. r=gps

The build system being what it currently is, there are various cases where one
wants something explicit, rather than the current autodetection.

For instance, one may want to run
  make -C $objdir chrome
instead of
  make -C $objdir/chrome
that mach build chrome currently invokes.

There are several such usecases that mach's autodetection makes harder, and
it's sometimes awkward when telling people, to debug their issues, to run
  make -C objdir something
and hear back that objdir doesn't exist or something along those lines,
because they took "objdir" literally.