LIT tests fail on Windows X86_64

[Tim Northover]

Hi Elena,

> 20>  FAIL: LLVM :: MC/AArch64/tls-relocs.s (4886 of 8256)

Thanks, I think I've seen something like this problem before and fixed
the test in r184667 (hopefully, I don't have Windows to do any testing
on). From what I remember, for some reason Windows output often gets
extra newlines in it; I'd be interested in the reasoning behind that,
if anyone knows.

Cheers.

Tim.