1.28 [KK 2007-02-15] Added small dependencies to src/Makefile. Added
     debugging code to http_header_add(). The signal handler (see
     interrupt.c) will exit immediately upon SIGPIPE when in serving
     mode. There is no need to wait for the current request to finish,
     when one of the network pipes has gone. Change exiting to _exit()
     instead of exit() to avoid cleanup code execution. Misc small
     changes in http mode.