patch: construct correct range when recovering member access as call

[Matt Beaumont-Gay]

On Wed, Aug 21, 2013 at 12:05 AM, Nick Lewycky <nlewycky at google.com> wrote:
> The attached patch adjusts the RParenLoc (end loc) used in the
> CXXMemberCallExpr that gets created in the recovery path when we see a
> non-call member access to a member function. (Ie., "foo->method" missing
> parenthesis). This is important to get right, or else the text diagnostic
> printer can assert.
>
> The bug is that it places the end sourcelocation at the end of the token
> (reusing the place where it wrote the fixit for inserting the "()") ,
> instead of the beginning of the last token.

Maybe add a comment about why we're not reusing ParenInsertionLoc.
FWIW, I'm not sure I understand the bug from the sentence above. Other
than that, LGTM.