This change fixes the formatting of statements such as catch (E& e).

Previously these were formatting as catch (E & e) because the inner parenthesis
was being marked as an expression.

Patch by Thomas Gibson-Robinson.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@188153 91177308-0d34-0410-b5e6-96231b3b80d8