hp에서 apache2 configure할때 오류

#./configure --prefix=/usr/local/apache2 --with-enable-shared=all --enable-so

이렇게 옵션을 주고 configure를 하는데 아래와같이 에러가 나더군요..

configure: WARNING: sys/sem.h: present but cannot be compiled
configure: WARNING: sys/sem.h:     check for missing prerequisite headers?
configure: WARNING: sys/sem.h: see the Autoconf documentation
configure: WARNING: sys/sem.h:     section "Present But Cannot Be Compiled"
configure: WARNING: sys/sem.h: proceeding with the preprocessor's result
configure: WARNING: sys/sem.h: in the future, the compiler will take precedence
configure: WARNING:     ## ------------------------------------------ ##
configure: WARNING:     ## Report this to the AC_PACKAGE_NAME lists.  ##
configure: WARNING:     ## ------------------------------------------ ##

위에 sem.h와 ipc.h만 컴파일이 안되는 거 같은데 왜 그런지..ㅠ.ㅠ

답변 부탁드립니다...