Revert "BoardConfig.mk: simplify BRIGHTNESS_SYS_FILE"

This reverts commit 1644df40303ad3fb250590df7b67aa55e94aa2ca.

Conflicts:

	boardconfig/BoardConfig.mk

 * We should keep track of every device BRIGHTNESS_SYS_FILE path as these should go under device/brand/variant/BoardConfig.mk file ideally
 * if no BRIGHTNESS_SYS_FILE path was defined, we should either IMMEADIATELY break compiling with a message error
 * eventually, we should add code to search for the brightness path in /sys on recovery load
Immediate error on missing needed flags for libtouch_gui
do not require libtouch_gui flags to be defined for non PhilZ Touch builds (Advanced Edition)
6.40.4
add function to find a file name in a given path
libtouch_gui 1.21: auto detect BRIGHTNESS_SYS_FILE path
    * only if it is not set during compile
    * search for the file in most common locations
    * if found, save it to recovery settings ini file to be called on next recovery starts
    * else, disable adjust brightness function to avoid error logs on recovery start
6.40.6
formatting fixes
fix various compiler error and warnings
6.40.7
libtar: add --numeric-owner option

We are not going to use this anymore in CWM like it was with mini config from Busybox
This way, the restore can be done based on user/group name rather than to uid/gid
This could potentially cause some applications to be broken when restored to a different ROM/system
dedupe: merge clean up code from @xiaolu
fix restorecon_from_file potential crash (by @xiaolu)
(only for BOARD_RECOVERY_USE_BBTAR)
fix 240x320 images
Sync with upstream:
- merge "cwm: Honor recovery variant "
- merge "cwm: Remove hardcoded paths"
- merge "Keep 'show log' on screen until user dismisses it"
always use inline make_ext4fs():
 * this applies to non vold managed extra storage when formatting to ext4 while no selinux context was defined
create /data/media directory after internal storage is wiped
  prevents denial to read/write from internal storage under some circumstances
6.41.4
Open source touch_gui library
Publish all inline comments
6.41.5