This commit adds a function that tokenizes the string containing
the machine instruction. This commit also adds a struct called
'MIToken' which is used to represent the lexer's tokens.
Reviewers: Sean Silva
Differential Revision: http://reviews.llvm.org/D10521
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240323 91177308-0d34-0410-b5e6-96231b3b80d8
