not on predefined values

The default name of the PID file was constructed, as documented, 
based on the hostname.  This name was subsequently used as the
base for the general log file name.   If the name of the PID
file was overridden in the configuration, and no explicit name
was set for the general log file, the path location for the
PID file was used also for the general log file.
                  
A new variable, 'default_logfile_name', has been introduced.  This name
is constructed based on the hostname, and is then used to
construct both the PID file and the general log file.
                  
The general log file will now, unless explicitly set, be
located in the server data directory (as documentated in
the server docs)


mysql-test/t/log_state.test:
  run/mysqld.log was created as a consequence of this bug.
  After the fix it is no longer created, and will thus not
  be deleted.