RFR (S, URGENT) 8149038: SIGSEGV at frame::is_interpreted_frame_valid -> StubRoutines::SafeFetchN

[Coleen Phillimore]

Summary: Backout change for 8146984 but add an alignment check which may 
have caught original bug.

Will retest with new check once this isn't an integration blocker. Ran 
original tests that failed.

open webrev at http://cr.openjdk.java.net/~coleenp/8149038.01/
bug link https://bugs.openjdk.java.net/browse/JDK-8149038

Thanks,
Coleen