When called from git-send-email, some results contain unclosed
parentheses from the subsystem title, for example:

    (cc-cmd) Adding cc: qemu-ppc@nongnu.org (open list:PowerNV (Non-Virt...) from: 'scripts/get_maintainer.pl --nogit-fallback'
    (cc-cmd) Adding cc: qemu-devel@nongnu.org (open list:All patches CC here) from: 'scripts/get_maintainer.pl --nogit-fallback'
    Unmatched () '(open list:PowerNV (Non-Virt...)' '' at /usr/lib/git-core/git-send-email line 642.
    error: unable to extract a valid address from: qemu-ppc@nongnu.org (open list:PowerNV (Non-Virt...)
    What to do with this address? ([q]uit|[d]rop|[e]dit): d

This commit removes all parentheses from results.

Signed-off-by: Emmanouil Pitsidianakis <manos.pitsidianakis@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20231013091628.669415-1-manos.pitsidianakis@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>