fix for bug 848926 GIS functions return "GEOMETRYCOLLECTION()" instead of "GEOMETRYCOLLECTION EMPTY"

per-file comments:
  mysql-test/r/gis.result
fix for bug 848926 GIS functions return "GEOMETRYCOLLECTION()" instead of "GEOMETRYCOLLECTION EMPTY"
        test result updated.
  mysql-test/t/gis.test
fix for bug 848926 GIS functions return "GEOMETRYCOLLECTION()" instead of "GEOMETRYCOLLECTION EMPTY"
        test case added.
  sql/gstream.cc
fix for bug 848926 GIS functions return "GEOMETRYCOLLECTION()" instead of "GEOMETRYCOLLECTION EMPTY"
        lookup_next_word() implemented.
  sql/gstream.h
fix for bug 848926 GIS functions return "GEOMETRYCOLLECTION()" instead of "GEOMETRYCOLLECTION EMPTY"
        lookup_next_word() added.
  sql/spatial.cc
fix for bug 848926 GIS functions return "GEOMETRYCOLLECTION()" instead of "GEOMETRYCOLLECTION EMPTY"
        name changed for the empty geometry.
  sql/spatial.h
fix for bug 848926 GIS functions return "GEOMETRYCOLLECTION()" instead of "GEOMETRYCOLLECTION EMPTY"
        declarations modified.