Contents of the 'debug.log':
CONFIGURE:   './configure' '--with-oci8' '--with-apxs=/projects/finnet/common/ap
ache-1.3.12-UX10.20/bin/apxs'
CC:         gcc
CFLAGS:     -g -O2
CPPFLAGS:   
CXX:        
CXXFLAGS:   
INCLUDES:    -I/projects/apache-1.3.12-UX10.20/include  -I$(top_builddir)/Zend -I$(top_srcdir) -I/usr1/build/php-4.0.0/ext/mysql/libmysql -I/usr1/oracle/8.0.5/rdbms/demo -I/usr1/oracle/8.0.5/network/public -I/usr1/oracle/8.0.5/plsql/public
LDFLAGS:     -L/usr1/oracle/8.0.5/lib -L/usr1/oracle/8.0.5/lib
LIBS:       -lclntsh -lpsa -lcore4 -lnlsrtl3 -l/usr/lib/libdld.sl -l/usr/lib/libcma.sl -lm -lcl -lm -lcrypt 
DLIBS:      
SAPI:       apache
PHP_RPATHS:  /usr1/oracle/8.0.5/lib
uname -a:   HP-UX hukka B.10.20 A 9000/778 2009325486 two-user license

gcc -o conftest -g -O2   -L/usr1/oracle/8.0.5/lib -L/usr1/oracle/8.0.5/lib conftest.c -lclntsh -lpsa -lcore4 -lnlsrtl3 -l/usr/lib/libdld.sl -l/usr/lib/libcma.sl
 -lm -lcl -lm -lcrypt  1>&5
collect2: ld returned 1 exit status
/bin/ld: Can't find library for -l/usr/lib/libdld.sl

--
I modified the -l/usr/lib/libdld.sl to -ldld and -l/usr/lib/libcma.sl to -lcma which seemed to correct this problem.