Moved include <assert.h> to my_global.h


VC++Files/client/mysqlclient.dsp:
  Added missing my_time.c file to mysqlclient project
include/my_dbug.h:
  Moved include <assert.h> to my_global.h
  Removed NDEBUG as asserts should be indenpendent of if we are using DBUG or not
include/my_global.h:
  Added assert.h as this is included in a lot of places
sql/sql_table.cc:
  Initialize forgotten variable