Check if installable before installing unstripped

When LOCAL_UNINSTALLABLE_MODULE is true, the module is not installed.
But its unstripped output is installed to the path based on
my_module_path which is not set for it is not installable. Moreover,
my_module_path is not reset after use.

As a result, when LOCAL_UNINSTALLABLE_MODULE is true, the path for
unstripped output is unexpected.

The installation is guarded by LOCAL_UNINSTALLABLE_MODULE now,
which was LOCAL_VNDK_DEPEND_ON_CORE_VARIANT.

Test: m
Change-Id: If18cf76118e058a9e0701a8d66f7ff0f534e5881