fault_handler: use SafeCopy to verify the validity of ArtMethod.

Reimplement ArtMethod::GetDeclaringClassUnchecked and VerifyClassClass
in terms of SafeCopy, to be able to safely verify the validity of
putative ArtMethods in FaultManager::IsInGeneratedCode.

Bug: http://b/30836730
Test: m test-art-host
Change-Id: Ie3d5e176ea569cedcefd320e2480a1e1e496a53a
1 file changed