patches: Add patch with signature for vasprintf

patches: Add patch with signature for vasprintf

Compilation step for __bsd_locale_fallbacks.h requires having a
signature for vasprintf.

This commit provides a patch that adds the needed function signature in
include/support/musl/xlocale.h, which will be included in
__bsd_locale_fallbacks.h.

Signed-off-by: Maria Sfiraiala <maria.sfiraiala@gmail.com>
Reviewed-by: Stefan Jumarea <stefanjumarea02@gmail.com>
Reviewed-by: Razvan Deaconescu <razvand@unikraft.io>
Approved-by: Razvan Deaconescu <razvand@unikraft.io>
Tested-by: Unikraft CI <monkey@unikraft.io>
GitHub-Closes: #23