Fix single-stepping resume mode in the interpreter.

Fix single-stepping resume mode in the interpreter.

When a resume attempt is cancelled due to other pending request make sure
the old native resume PC is cleared. Otherwise the JIT code cache may be
re-entered with mismatching Dalvik PC.

Also fix a code bloat problem where single-step count is not set properly
after executing a return instruction.

Change-Id: Ia926bc3a87cae1296719a1069838060b181ce54d