to create libflint.so.X -> libflint.so.X.Y.Z link on SunOS
to create libflint.so.X -> libflint.so.X.Y.Z link on SunOS

This is essentially the same workaround as for FreeBSD:
https://github.com/wbhart/flint2/pull/347
With the structure already in place we just need to special-case SunOS

fredrik-johansson/flint2,wbhart/flint2,wbhart/flint2,fredrik-johansson/flint2,wbhart/flint2,fredrik-johansson/flint2