In debug output, show waitpid status with 6 hex digits, not 4

This shows event byte values better (without variable offset):

 [wait(0x01057f) = 29491] WIFSTOPPED,sig=SIGTRAP,EVENT_FORK (1)
 [wait(0x80057f) = 29492] WIFSTOPPED,sig=SIGTRAP,EVENT_STOP (128)
         ^^

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
1 file changed