build: Add chromium prebuilt support to envsetup.sh && The core Makefile

This adds a chromium_prebuilt function to envsetup.sh that is invoked by lunch to check
whether the chromium prebuilts are up-to-date or not. If not, it will be built from source
and then the new source built version will be pulled during brunch/mka bacon to become the
new prebuilts for future builds.

This is all opt-in through the USE_PREBUILT_CHROMIUM flag. Without it being set to 1,
none of this would be ran, and regular operations will go on.

PS13:
-use export TARGET_DEVICE
-replace git -C with params compatible to old git versions

Change-Id: I40f8c8dbd2a8a84a5c1b9f47ee04180a71ef4e07
Revert "FM Radio: Add support for FM Radio in Android"

 * fmradio folder is not currenly present in frameworks/base,
   so remove the inclusion of it to avoid warnings during build.

This reverts commit ef83ac85d91285eeb7c567cd93a5c83d2fa7714d.

Change-Id: I38af983ed74e0ee36172ad5e934ca48529760fb6
Make repopick support gerrit 2.9

Change-Id: I5b5fcfdfb69fd8639a7170f68966817ba1bb98b7
Merge "Revert "FM Radio: Add support for FM Radio in Android"" into android-4.4
Merge pull request #14 from omnirom/android-4.4

:D