Be on the safe side: emit an environment for runtime calls.

Even if those runtime calls don't throw, they may be interrupted
and be asked to dump their stack. Since dumping a stack also dumps
locked Java objects, we need a DexRegisterMap at these locations
to know the location of those objects.

Adds 0.05% to boot image code size.

bug:26168076
Change-Id: I7c3975addea9ddf3123183b07108b0701bb26fc8