Add more AFDO tests

Add more coverage to the afdo tests for the arm32 variant of a module
that only has an arm64 profile, for the -funique-internal-linkage-names
flag, and for the interaction between LTO linker flags and AFDO.

Test: afdo_test.go
Change-Id: I3ed4ce033c2431ea3e2fee536744b5e5b4cad296