Samsung msm7x27-common: cleanup & reorganize shared config

* Fixup building with BlueZ or Bluedroid (BlueZ not yet backported
  to CM10.2)
* Cleanup init.rc files, and remove duplicate fstab.msm7x27
* Add usbhost entry to fstab.msm7x27 to prevent vold failure in apps
* Move overlay, board config, recovery code and properties that are
  common for all builds into shared config; duplicate config will be
  removed from per-device repositories in separate commits
* Build hwcomposer on all kernel targets
* Disable dalvik alloc debug output (dalvik.vm.debug.alloc=0)
* Add more useless files to releasetools-extras.txt for space savings
* Remove all kernel headers
* Adjust libaudio to use headers from kernel source
* Recovery: remove recovery.rc, non-working graphics.c
* Recovery: use default init.rc, add minimal init.msm7x27.recovery.rc
  (to insmod fsr drivers and configure USB drivers for adbd properly)
* Recovery: assign home key to select function, disable menu key
* ath6kl: update ath6kl-compat building, fix wifi AP interface name

Change-Id: I066df7095a94bf996e731ddaa3f70e182206469b