Cleaned up xxxx_gis.test's and made gis_generic.inc independent of ndb
(Note that archive_gis.test fails, but this is independent of this patch)


client/mysqldump.c:
  Add DROP TABLE to be able to re-run mysqldump if it fails after 'table-named-as-view' is created
mysql-test/include/gis_generic.inc:
  Remove dependency of ndb
mysql-test/include/have_archive.inc:
  Fix syntax
mysql-test/include/have_geometry.inc:
  Fix syntax
mysql-test/r/mysqldump.result:
  New test results after adding 'drop table'
mysql-test/t/archive_gis.test:
  gis_generic tests for have_geometry.inc
mysql-test/t/bdb_gis.test:
  gis_generic tests for have_geometry.inc
mysql-test/t/innodb_gis.test:
  gis_generic tests for have_geometry.inc
mysql-test/t/ndb_gis.test:
  gis_generic tests for have_geometry.inc
sql/item_func.cc:
  Simplify code (as signal_divide_by_null sets 'null_value')