While the seccomp sandbox appears to work correctly when built with "clang", the unittest was still failing. It turns out that clang's built-in assembler turns all short jumps into long jumps. The unittest inspects the generated instructions to verify that backtraces of instrumented system calls look the way that we expect them to do. And of course, the signature no longer matches if the assembler outputs a different sequence of bytes than what we tried to tell it.
While the seccomp sandbox appears to work correctly when built with "clang",
the unittest was still failing. It turns out that clang's built-in assembler
turns all short jumps into long jumps. The unittest inspects the generated
instructions to verify that backtraces of instrumented system calls look the
way that we expect them to do. And of course, the signature no longer matches
if the assembler outputs a different sequence of bytes than what we tried to
tell it.

This changelist makes the unittest more tolerant of different instruction
streams.

BUG=http://code.google.com/p/chromium/issues/detail?id=70871
TEST=Build with clang, then run "make test"
Review URL: http://codereview.chromium.org/7533008

git-svn-id: c2a6f690695ec6703fa4e0d44c2dfcc6697c486d@164 55e79e8e-603c-11de-8c10-5fe6993ea61f

mseaborn/seccompsandbox,mseaborn/seccompsandbox,mseaborn/seccompsandbox