Teach typo correction about various language keywords. We can't
generally recover from typos in keywords (since we would effectively
have to mangle the token stream). However, there are still benefits to
typo-correcting with keywords:
  - We don't make stupid suggestions when the user typed something
  that is similar to a keyword. 
  - We can suggest the keyword in a diagnostic (did you mean
  "static_cast"?), even if we can't recover and therefore don't have
  a fix-it.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@101274 91177308-0d34-0410-b5e6-96231b3b80d8
13 files changed