configure.in:
  ./configure now tests if gmtime_r is present
include/config-os2.h:
  Supposing that OS/2 have gmtime_r
include/my_pthread.h:
  Use our imeplementation of gmtime_r if system lacks one
mysql-test/r/func_time.result:
  Added UTC_* functions to test
mysql-test/t/func_time.test:
  Added UTC_* functions to test
mysys/my_pthread.c:
  Our implementation of gmtime_r
mysys/my_thr_init.c:
  Now we also need LOCK_locktime_r if gmtime_r is absent
sql/item_timefunc.cc:
  Generalized classes for CURDATE, CURTIME and NOW, abstracted them from
  timezone. Added new children classes for implementing these and UTC_*
  functions.
sql/item_timefunc.h:
  Generalized classes for CURDATE, CURTIME and NOW, abstracted them from
  timezone. Added new children classes for implementing these and UTC_*
  functions.
sql/lex.h:
  Added tokens for UTC_TIME, UTC_DATE and UTC_TIMESTAMP
sql/sql_yacc.yy:
  Added UTC_* functions to grammar. Current functions are using 
  classes now.