Enable -funique-internal-linkage-names when afdo=true

We used to enable unique names only when a profile is available.
But A profile generated for a binary without unique names doesn't
work well when building a binary with unique names. To avoid a
chicken-and-egg problem, this CL enables the flag when afdo=true,
whether a profile exists or not.

Bug: 241523910
Test: build
Change-Id: I74d834510d81d2db76e34d0488c74a60e1fcecd5