Skip checking ELF files for uninstallable soong modules

If a module is uninstallable, the shared library dependencies are not
set up and thus the ELF file check may fail incorrectly.  In this case,
there is no need to check ELF files anyway.

Test: Build walleye with no-vendor-variant VNDK enabled and does not
      see erroneous failure anymore.

Change-Id: Icd115fc82daedf11795800de5cbe87c87073586a