build: Don't ignore qapi-visit-core.c

This file is version-controlled, and not generated from a .json file.

Fixes: bf582c3461b
Reported-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190912184607.3507-1-eblake@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
1 file changed