Then when we have an integrated assembler, we can check
its disassembly and the result should be the same.
This only touches the tests that invoke llvm-mc currently.
There are other tests which check for .s file output.

There are quite a bit of quirks with llvm-objdump,
which is unfortunate:

(*) The symbolizer doesn't pick up non-section-local
function calls. Some externals were converted to be
local functions. Workaround: where it counts, I just
left a check via .s files and a new --check-prefix.
It's a little better in 3.6.

(*) The symbolizer doesn't pick up global variable names.
I just checked for the relocation addend instead.
Didn't check if it was better in 3.6, but maybe.

(*) We have a bug in bundling lock + instructions.
See
BUG=https://code.google.com/p/nativeclient/issues/detail?id=3929

(*) There's no disassembly for branch lables.
Checks of jump instructions were converted to check
for positive or negative values, depending on whether
it is a forward or backward branch.

BUG=none
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/509233002