ngIRCd already includes <sys/types.h> in a lot of places without
checking for its existence (for example in "ngircd.c", "io.c", ...),
therefore make it a required header file.
# Required header files
AC_CHECK_HEADERS([ \
fcntl.h netdb.h netinet/in.h stdlib.h string.h \
- strings.h sys/socket.h sys/time.h unistd.h \
+ strings.h sys/socket.h sys/time.h sys/types.h unistd.h \
],,AC_MSG_ERROR([required C header missing!]))
# Optional header files