gpg: Prepare for globing with UTF-8.

* g10/gpg.c (_dowildcard): Remove.
(my_strusage): Enable wildcards using our new system.

This patch actually removes the current globing using a mingw
feature. We are not able to use this because it does not handle
Unicode filenames. The plan is to implement this in init.c. This
patch merely configures gpg to request globing.

(cherry picked from commit 8e15506d6680bbee85bc01453da28fc90b4cb673)

• GnuPG-bug-id: T4398