build: Clean up use of vendor/extra

 * extra_config.mk is not needed anymore
 * Include BoardConfigExtra.mk if available

Change-Id: Icd0db0852ceee5cb5c701c9a40b829e1f3ebd69e
Enable gesture typing - (3/3)-delete the libjni_latinime package in favour of prebuilt libjni_latinime

Change-Id: Id06777518f0d0e87aaeab8fb105224ae29ed9e77
Fixes for gcc 4.8/4.9

Change-Id: I498ab5fd5ef97b21e365dbcac6110eabaec5d289