Report fatal errors instead of segfaulting/asserting on a few invalid accesses...

Report fatal errors instead of segfaulting/asserting on a few invalid accesses while reading MachO files.

Summary:
Shift an older “invalid file” test to get a consistent naming for these tests.

Bugs found by afl-fuzz

Reviewers: rafael

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D6945

llvm-svn: 226219