Let extra compiler/linker flags be supplied in the environment.

https://bugzilla.mozilla.org/show_bug.cgi?id=850041

Names are formed by inserting `EXTRA_` after the `HOST_` or `TARGET_`.
Merge pull request #20 from jld/extra-build-flags-master

Let extra compiler/linker flags be supplied in the environment. r=dhylands
Revert "Bug 834244 - Switch to new font set"

This reverts commit c4cc32e04d1d5f24f0d962f9608879bd8e0bff66.

Switch back to the old set of fonts for now.
Bug 834244 - Switch to b2g.mk in gonk-misc to switch to new set of fonts
Bug 852583: enable bluetooth on emulator
Merge pull request #21 from vicamo/bluetooth

Bug 852583: enable bluetooth on emulator