Fix generic jni issue in ArtMethod::GetQuickFrameInfo

The 64-bit host mode fails to start due to incorrect
detection of GetQuickGenericJniTrampoline.
The quick_code is 32-bit and taken from oat file, but
GetQuickGenericJniTrampoline returnf 0x7fffxx (64-bit)
address of trampoline and execution went to incorrect way.

Some clean-up.

Original Author: Dmitry Petrochenko <dmitry.petrochenko@intel.com>
Signed-off-by: Dmitry Petrochenko <dmitry.petrochenko@intel.com>
Signed-off-by: Serguei Katkov <serguei.i.katkov@intel.com>
Change-Id: I0952443b2a9f6833ad37ec373837ae208681fad7