Use different method to mark DEX PC in the interpreter's CFI.

gdb handles unknown register numbers very ungracefully, so
we have to find a different way to insert the information.

Test: testrunner.py -j40 --host --cdex-fast -t 137
Change-Id: Ie4f8abb45e1b4ade32a510ac09413c6ee72edf2c
20 files changed