Here are the interesting portions from your build logs.

===> Building for ap2-php-4.2.3
[...]
cc -I. -I/usr/pkgsrc/www/ap2-php4/work/php-4.2.3/sapi/apache2filter -I/usr/pkgsrc/www/ap2-php4/work/php-4.2.3/main -I/usr/pkgsrc/www/ap2-php4/work/php-4.2.3 -I/usr/pkg/include/httpd -I/usr/pkg/include/apr-0 -I/usr/pkgsrc/www/ap2-php4/work/php-4.2.3/Zend -I/usr/pkgsrc/www/ap2-php4/work/php-4.2.3/TSRM -I/usr/pkg/include -O2 -I/usr/pkg/include -c sapi_apache2.c  -fPIC -DPIC -o sapi_apache2.lo
sapi_apache2.c:31: apr_strings.h: No such file or directory

===> Building for ap2-perl-1.99.8
cd "src/modules/perl" && make -f Makefile.modperl
cc -I/usr/pkgsrc/www/ap2-perl/work/mod_perl-1.99_08/src/modules/perl -I/usr/pkgsrc/www/ap2-perl/work/mod_perl-1.99_08/xs -I/usr/pkg/include/apr-0 -I/usr/pkg/include/httpd -fno-strict-aliasing -I/usr/pkg/include  -I/usr/pkg/lib/perl5/5.6.1/i386-netbsd/CORE -DMOD_PERL -O2 -I/usr/pkg/include -DPIC -fPIC  -c mod_perl.c && mv mod_perl.o mod_perl.lo
In file included from /usr/pkgsrc/www/ap2-perl/work/.buildlink/include/httpd/httpd.h:72,
                 from modperl_apache_includes.h:11,
                 from mod_perl.h:4,
                 from mod_perl.c:1:
/usr/pkgsrc/www/ap2-perl/work/.buildlink/include/httpd/ap_config.h:58: apr.h: No such file or directory

Note that in each one the apr include directory *is* listed.
Something is really screwed on your system.  Do you actually have
the apr headers in /usr/pkg/include/apr-0?

--  
Eric Gillespie <*> epg@pretzelnet.org

Build a fire for a man, and he'll be warm for a day.  Set a man on
fire, and he'll be warm for the rest of his life. -Terry Pratchett