Remove PIC option from oat files.

dex2oat has been producing only PIC code for some time,
so there's no need to record it in the oat file anymore.
Also get rid of the now unnecessary relocation logic
that was using the flag.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Test: Pixel 2 XL boots.
Test: m test-art-target-gtest
Test: testrunner.py --target --optimizing
Bug: 77856493
Change-Id: I070071ca5a808371f67883f4ae93d633a76231d0