[MC] - llvm-mc hangs on non-english characters.

Currently llvm-mc just hangs inside infinite loop
while trying to parse file which has ".section .с" inside,
where section name is non-english character.
Patch fixes the issue.

In this patch I also moved content of non-english-characters.s
to test/MC/AsmParser/Inputs folder  so that non-english-characters.s
becomes a single testcase for all invalid inputs containing non-english
symbols. That is convinent because llvm-mc otherwise tries
to parse and tokenize the whole testcase file with tools invocations and
it is harder to isolate the issue.

Differential revision: https://reviews.llvm.org/D38545

llvm-svn: 314973