The PHP3 configure script makes incorrect assumptions about the location of LIB and INCLUDE paths for PostgreSQL 6.3.x (and earlier ?) on Red Hat Linux 5.x (and earlier ?). When PostgreSQL is installed using the RPM packages provided by Red Hat, the INCLUDE directory is /usr/include/pgsql and the LIB directory is /usr/lib. configure assumes that both directories are braches off a common directory, as in /BASE/DIRECTORY/include and /BASE/DIRECTORY/lib.

I fixed the problem by changing the configure script to default to the RPM-provided paths, but those changes will probably break the script on other non-RPM operating systems. Perhaps a more flexible solution would be for configure to check for the existance of the RPM paths indicated above, and use them if available, otherwise fall back to the /BASE/DIRECTORY/... configuration that you use now.