This allows "llvm-mc -disassemble" to accept two new features:
+ Using comma as a byte separator
+ Grouping bytes with '[' and ']' pairs.
The behaviour outside a [...] group is unchanged. But within the group once
llvm-mc encounters a true error, it stops rather than trying to resynchronise
the stream at the next byte. This is more useful for disassembly tests, where
we have an almost-instruction in mind and don't care what the misaligned
interpretation would be. Particularly if it means llvm-mc won't actually see
the next intended almost-instruction.
As a side effect, this means llvm-mc can disassemble its own -show-encoding
output if copy-pasted.
llvm-svn: 186661
