apex: AndroidMk writes common properties

AndroidMkEntries handles bunch of common properties(e.g. LOCAL_INIT_RC,
LOCAL_VINTF_FRAGMENTS, etc).

However apex defines its own Custom() writer, so those properties should
be handled manually.

For example, when an apex defines "init_rc" properties, the value should
be passed to Make via LOCAL_INIT_RC.

Bug: 159211312
Test: m
Change-Id: I65e7a456486c9f5fe70c91b78ff181425035fcf2