With this change, you can easily switch between building from source
code and prebuilt.
Set LOCAL_PREBUILT_MODULE_FILE to the path of the prebuilt file,
relative to the top of the source tree, in the usual module definition.
The prebuilt will be used unless any of the followings satisfied:
1) ANDROID_BUILD_FROM_SOURCE is "true", which disable prebuilt globally;
2) The module name is in ANDROID_NO_PREBUILT_MODULES;
3) The LOCAL_PATH is prefixed by any of ANDROID_NO_PREBUILT_PATHS.
A developer can set ANDROID_NO_PREBUILT_MODULES or
ANDROID_NO_PREBUILT_PATHS to build only his own module(s) from source,
while build other modules from prebuilts.
You can set ANDROID_BUILD_FROM_SOURCE to true to build everything from
source.
Those variables can be set with shell environmental variable or in your
buildspec.mk.
Sometimes module B is able to be built from source only if module A is
also
built from source, for example, if B is the test apk of A.
In that case, you can use the macro include-if-build-from-source to
include B's Android.mk only if A is built from source too, or
if-build-from-source to conditionally include the definition of module
B,
if their module definitions are in the same Android.mk.
Support host-executable-hook and host-shared-library-hook.
Change-Id: Icab7cf028c87eaba0dd7efc2a7749fd6f32b44e4
