Add warning group -Woverloaded-shift-op-parentheses to -Wparentheses. This

will fire on code such as:

  cout << x == 0;

which the compiler will intrepret as

  (cout << x) == 0;

This warning comes with two fixits attached to notes, one for parentheses to
silence the warning, and another to evaluate the comparison first.

llvm-svn: 179662