Fix parsing of return statements.

Previously, we would not detect brace initializer lists in return
statements, thus:
 return (a)(b) { 1, 2, 3 };
would put the semicolon onto the next line.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@173017 91177308-0d34-0410-b5e6-96231b3b80d8