[Bug] v.random doesn't strip mapset from column names

[marisn]

If a fully qualified vector map name is passed as a restrict parameter, it is used to create columns in target table in verbatim. As FQN is in form map@mapset and the value is not escaped or quoted, it causes an SQL error. Instead of using plain param.input->answer for a column name, only the map part should be passed here. https://github.com/OSGeo/grass/blob/da182541396a29288e8f23a66bd3a7150eb8fe4e/vector/v.random/main.c#L291