Sema: handle additional case of qualified types

A second instance of attributed types escaped the previous change, identified
thanks to Richard Smith!  When deducing the void case, we would also assume that
the type would not be attributed.  Furthermore, properly handle multiple
attributes being applied to a single TypeLoc.

Properly handle this case and future-proof a bit by ignoring parenthesis
further.  The test cases do use the additional parenthesis to ensure that this
case remains properly handled.

Addresses post-commit review comments from Richard Smith to SVN r219851.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@219974 91177308-0d34-0410-b5e6-96231b3b80d8
Re-commit r217995 and follow-up patches (r217997, r218011, r218053). These were
reverted in r218058 because they triggered a rejects-valid bug in MSVC.

Original commit message from r217995:

Instantiate exception specifications when instantiating function types (other
than the type of a function declaration). We previously didn't instantiate
these at all! This also covers the pathological case where the only mention of
a parameter pack is within the exception specification; this gives us a second
way (other than alias templates) to reach the horrible state where a type
contains an unexpanded pack, but its canonical type does not.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@219977 91177308-0d34-0410-b5e6-96231b3b80d8