Gracefully handle an attribute specifier following a lambda introducer when the parameter list wasn't present.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@203565 91177308-0d34-0410-b5e6-96231b3b80d8
Changing this test case to use an unknown attribute, since there are not currently any type attributes which would apply to a lambda, except in MSVC compatibility mode.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@203566 91177308-0d34-0410-b5e6-96231b3b80d8