ia64-hp-hpux11.23 configure warnings

checking build system type... ia64-hp-hpux11.23
checking host system type... ia64-hp-hpux11.23
...
checking sys/ipc.h presence... yes
configure: WARNING: sys/ipc.h: present but cannot be compiled
configure: WARNING: sys/ipc.h:     check for missing prerequisite headers?
configure: WARNING: sys/ipc.h: see the Autoconf documentation
configure: WARNING: sys/ipc.h:     section "Present But Cannot Be Compiled"
configure: WARNING: sys/ipc.h: proceeding with the preprocessor's result
configure: WARNING: sys/ipc.h: in the future, the compiler will take precedence
configure: WARNING:     ## ---------------------------------------- ##
configure: WARNING:     ## Report this to pgsql-bugs@postgresql.org ##
configure: WARNING:     ## ---------------------------------------- ##


There are several more of these sorts of warnings in the
attached complete configure output.

Thanks,
Ed