wl #1163 (Make spatial code optional)
Patch I cleaned with Serg & Monty's suggestions


sql/gen_lex_hash.cc:
  mysql_priv.h was included for SYM_GROUP declaration
sql/lex.h:
  sym_group_xxx made global so we can use texts from them
  throughout the code
sql/lex_symbol.h:
  SYM_GROUP declaration moved to mysql_priv.h
sql/mysql_priv.h:
  declarations about SYM_GROUP
sql/sql_table.cc:
  sym_group_xxx objects used instead of text constants
  a couple of HAVE_SPATIAL removed
sql/sql_yacc.yy:
  sym_group_xxx used instead of text constants
  some duplicated code restructured
  MYF(0) parameters removed from net_printf calls