enable bionic optimizations on cortex-a5

Change-Id: I7b687e0dabbb155fa426d89e84358504d22b93b9
build: Add support for extra kernel build variables

 * This allows specifying a variant defconfig, and an selinux defconfig
   which are simply configuration fragments.

Change-Id: I97882ae3b8c2e16ff6a7dce8dd3a70d70f8aa866
Fix /system/app/$app.odex not updated issue

$(built_odex) depends on $(LOCAL_BUILT_MODULE) but doesn't have any build
recipe. It is built by the rules of $(LOCAL_BUILT_MODULE) that results in
a subtle bug: $(built_odex) is always newer than $(LOCAL_BUILT_MODULE)
if $(LOCAL_BUILT_MODULE) rebuilt. Therefore 'make' thinks the targets
(/system/app/$app.odex) depending on $(built_odex) don't need to be updated.
It seems an allegedly optimization bug of 'make'.

The simple fix is to explicitly add $(LOCAL_BUILT_MODULE) as a dependency
of $(installed_odex).

Change-Id: Ia62695eeb9a9709f7115301cbf27eb1fd77a1573