autobuild: add autobuild scripts

   The autobuild scripts provide an unified way
   to build agl apps & services; for the agl
   modules missing these scripts, a workaround is
   in place to warn of this scenario and allow
   for build completion.
   This commit add these missing scripts for hvac
   app withoud modifying the existing qmake files.
   The original scripts, which were designed for
   cmake use, are slimmed down and adapted to use
   qmake.

   - autobuild/agl/autobuild: allows aglwgt_package
   task to complete, eliminating the verbose
   warnings.
   - autobuild/linux/autobuild: allows to build
   the wgt file natively on linux using the agl
   sdk.

Change-Id: I609e59c2915833f44dbdfc006fba15a8841f3c5f
Bug-AGL: SPEC-2164
Signed-off-by: Raquel Medina <raquel.medina@konsulko.com>