Additional info: THe apache error_log has:
httpd: error in loading shared libraries:
/usr/lib/apache/php_mapscript.so: undefined symbol:
_register_list_destructors
in it. So this looks like the problem, but How do I fix it?
This happens if your php executable (if you compiled PHP as a CGI) or
your httpd binary (if PHP is compiled statically into Apache) was not
linked to support loading shared libraries. It has to be relinked using
the "-rdynamic" option (on Linux) which will allow loading of shared
libraries.