Reenable 'break' in 'for' specifier to allow compilation of QT macro 'foreach'

This is a fix to PR17649, caused by fix in r193073. QT uses 'break' statement
to implement their 'foreach' macro. To enable build of QT, this fix reenables
break but only in 'for' statement specifier and only in the third expression.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@193170 91177308-0d34-0410-b5e6-96231b3b80d8