statements and negative time/date values". 
The bug was in wrong sprintf format used in the client library.
The fix moves TIME -> string conversion functions to sql-common and
utilized them in the client library.


include/my_time.h:
  Declarations for new functions shared between the client and server.
libmysql/libmysql.c:
  Fix for Bug#6049 "Loss of sign when using prepared statements and negative
  time/date values": use the same function as the server to convert
  date/time/datetime values to strings.
sql-common/my_time.c:
  Implementation of my_{time,datetime,date,TIME}_to_str: it's
  needed by the client library, so it should be shared.
sql/field.cc:
  Don't create String object if it's not needed.
sql/item.cc:
  Don't create String object if it's not needed: TIME_to_string was
  moved to my_TIME_to_str, with different arguments.
sql/item_timefunc.cc:
  Don't create String object if it's not needed.
sql/mysql_priv.h:
  TIME_to_string and MAX_DATE_REP_LENGTH moved to the client library.
  MAX_DATE_REP_LENGTH was renamed to MAX_DATE_STRING_REP_LENGTH to not 
  conflict with the same name in libmysql.c
sql/protocol.cc:
  Don't create String object if it's not needed.
sql/time.cc:
  Implementation of my_{time,date,datetime,TIME}_to_str moved to my_time.c
  shared between the client and the server.
tests/client_test.c:
  A test case for Bug#6049.