Don't install rust modules that are never installable

rust modules that return false on EverInstallable don't get installed.
Currently, proc_macro modules are such ones.

Bug: 187810017
Test: m microdroid on aosp_arm64 and inspect that *.dylib.so files
from host x86_64 are not there.

Change-Id: Ia57289a04dbff6e4f2ce2733c60de5338305904c