built-in stash: handle :(glob) pathspecs again

built-in stash: handle :(glob) pathspecs again

When passing a list of pathspecs to, say, `git add`, we need to be
careful to use the original form, not the parsed form of the pathspecs.

This makes a difference e.g. when calling

	git stash -- ':(glob)**/*.txt'

where the original form includes the `:(glob)` prefix while the parsed
form does not.

However, in the built-in `git stash`, we passed the parsed (i.e.
incorrect) form, and `git add` would fail with the error message:

	fatal: pathspec '**/*.txt' did not match any files

at the stage where `git stash` drops the changes from the worktree, even
if `refs/stash` has been actually updated successfully.

This fixes https://github.com/git-for-windows/git/issues/2037

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>