I did as it says in the INSTALL of php and the as it says in the INSTALL of apache and I get the same error:

 + doing sanity check on compiler and options
** A test compilation with your Makefile configuration
** failed.  The below error output from the compilation
** test will give you an idea what is failing. Note that
** Apache requires an ANSI C Compiler, such as gcc. 

cd ..; gcc -O2 -DSOLARIS2=280 -I/usr/local/php-4.0.0 -I/usr/local/php-4.0.0/Zend -I/usr/local/php-4.0.0/Zend -I/usr/local/php-4.0.0 -DMOD_SSL=206102 -I/usr/local/php-4.0.0 -I/usr/local/php-4.0.0/Zend -I/usr/local/php-4.0.0/Zend -I/usr/local/php-4.0.0 -DEAPI -DEAPI_MM -DUSE_EXPAT -I./lib/expat-lite `./apaci` -I/net/neblina/usr/local/mm-1.1.2  -L/net/neblina/usr/local/openssl-0.9.5a -L/net/neblina/usr/local/mm-1.1.2/.libs  -o helpers/dummy helpers/dummy.c   -Lmodules/php4 -L../modules/php4 -L../../modules/php4 -lmodphp4  -ldb -lpam  -ldl -lresolv -lresolv -lm  -lsocket   -Lmodules/php4 -L../modules/php4 -L../../modules/php4 -lmodphp4  -ldb -lpam  -ldl -lresolv -lresolv -lm  -lsocket  -lsocket -lnsl  -lssl -lcrypto -lmm -ldl
ld: fatal: library -lmodphp4: not found
ld: fatal: library -lmodphp4: not found
ld: fatal: File processing errors. No output written to helpers/dummy
collect2: ld returned 1 exit status
make: *** [dummy] Error 1
======== Error Output for sanity check ========
============= End of Error Report =============

I installed the php4
weitepuy:apache_1.3.12# ls -l src/modules/php4/
total 246
-rw-------   1 root     other        252 Jun 21 14:12 Makefile.libdir
-rw-------   1 root     other       2246 Jun 21 14:12 Makefile.tmpl
-rw-------   1 root     other        326 Jun 21 14:12 libphp4.module
-rw-------   1 root     other      22064 Jun 21 14:12 mod_php4.c
-rw-------   1 root     other         12 Jun 21 14:12 mod_php4.exp
-rw-------   1 root     other       1718 Jun 21 14:12 mod_php4.h
-rw-------   1 root     other      94976 Jun 21 14:12 mod_php4.lo