Fix pointer formatting in crash handler output.

Do not use 0x%p to output thd address, use %p

Author: vaintroub

sql/signal_handler.cc

@@ -143,7 +143,7 @@ extern "C" sig_handler handle_fatal_signal(int sig)
 
  if (opt_stack_trace)
  {
- my_safe_printf_stderr("Thread pointer: 0x%p\n", thd);
+ my_safe_printf_stderr("Thread pointer: %p\n", thd);
  my_safe_printf_stderr("%s",
  "Attempting backtrace. You can use the following "
  "information to find out\n"