Modify the frame context memory deallocation

Modify the frame context memory deallocation

This patch was to fix the vpxdec fuzzing3 test failure. When an
error occurs, setjmp() is invoked, which calls the decoder
removing routine. In multiple thread situation, other threads
could try to access the frame context memory that is already
deallocated, thus causing a segfault.

An invalid unit test was added for this issue.

Change-Id: Ida7442154f3d89759483f0f4fe0324041fffb952