Clean up linker patches in codegens.

In preparation for introducing boot image extension, make
sure that we can use both kBootImageLinkTimePcRelative and
kBootImageRelRo load kinds at the same time.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Test: aosp_taimen-userdebug boots
Test: run-gtests.sh
Test: testrunner.py --target --optimizing
Change-Id: I340f2d7d19e1c20699b37b0304d2e487d497da98
12 files changed