Change TRUNCATE(number) to truncate towards zero for negative numbers
Fix NULL handling for DESCRIBE table_name


Docs/manual.texi:
  Update of TRUNCATE() information
configure.in:
  Fix for HPUX
extra/resolveip.c:
  Fix for SCO
include/my_net.h:
  Fix for HPUX
libmysql/libmysql.c:
  Removed warning on HPUX 10.20
mysql-test/r/func_math.result:
  Test of new TRUNCATE handling
mysql-test/t/func_math.test:
  Test of new TRUNCATE handling
mysys/my_gethostbyname.c:
  Portability fix
sql/item_func.cc:
  Change TRUNCATE(number) to truncate towards zero for negative numbers
sql/sql_show.cc:
  Fix NULL handling for DESCRIBE table_name