end-of-line check missed in Gis_read_stream::get_next_word,
what can lead to crashes (expecially with NULL strings).

End-of-line check added


sql/gstream.cc:
  Bug #30955 geomfromtext() crasher
mysql-test/r/gis.result:
  Bug #30955 geomfromtext() crasher.
  
  test result
mysql-test/t/gis.test:
  Bug #30955 geomfromtext() crasher.
  
  test case