Implement -Wparentheses:  warn about using assignments in contexts that require
conditions.  Add a fixit to insert the parentheses.  Also fix a very minor
possible memory leak in 'for' conditions.

Fixes PR 4876 and rdar://problem/7289172



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@83907 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed