CFI compatibility with static executables and nested archives

This CL makes the following changes:
(a) It disables diagnostics for CFI which requires the runtime ubsan
library (which isn't included in static executables).

(b) It applies the ar flags for CFI correctly for nested .a
archives.

(c) Applies the version script to export CFI shadow for non-static
binaries

(d) Doesn't apply cross-dso CFI for static executables

Bug: 30227045
Test: Static executables build correctly and do not complain about
missing symbols from the ubsan runtime library.
Test: Nested .a files correctly use the gold plugin.

Change-Id: Id8fe3c13f6b76565aafbf1266e95f50d1447a790