x11/xmascot: clean up port
- fix build with -fno-common and un-expire
- set LICENSE
- fix parallel build
- move to MASTER_SITE of submitter
Add entry to LEGAL
Submitter becomes maintainer
PR: 249011
MFH: 2021Q2
(cherry picked from commit ffce9c1d6dfcfacb319eed3c02c2d2dc4f44bd46)