Bug 944558 - Refactor config/makefiles/debugmake.mk for more correctness, and remove old cruft. r=gps

Also remove use of print-depth-path.sh in UPDATE_TITLE.
Bug 944835 - Fix non-unified build in layout/base after bug 941559. r=roc
Bug 944830 - Fix non-unified build in gfx after bug 942492, bug 943293 and bug 944172. r=bjacob