splittiln common client's parts


include/sql_common.h:
  superfluous #ifdef-s removed
libmysql/client_settings.h:
  superfluous #ifdef-s removed
libmysql/libmysql.c:
  some litter removed
libmysqld/lib_sql.cc:
  here we had wrong parameters
mysys/default.c:
  this is not needed anymore - calling code fixed
sql-common/client.c:
  code trimmed and simplified
sql/client_settings.h:
  code trimmed
sql/repl_failsafe.cc:
  option's initialization added
sql/slave.cc:
  option's initialization added