.mailmap: add (another) entry for Liming Gao

... for git-shortlog purposes.

NOTE: this patch does not introduce a cross-domain mapping; it only maps
the name "gaoliming" in Liming's new email address to "Liming Gao" (see
the Author field on commit aad9cba8).

Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>