Fix unwinding for art_quick_generic_jni_trampoline

DELIVER_PENDING_EXCEPTION spills LR which is unused/garbage.
This breaks backtraces when the unwinder tries to follow it.

Add trivial call so that the LR is initialized.
(spills at the start of method are expected and working)

Bug: 187632012
Test: test.py -r --gcstress --all-run -t 1927 -t 178
Change-Id: I151aa7595f9fd90169402187066a04efba5d54c9
4 files changed