the php compiles fine, however apache barfs on the module using:

#configure --prefix=/usr/local/apache \
  --activate-module=src/modules/php4/libphp4.a \
  --enable-module=php4

#make

...

gcc  -DLINUX=2 -I/usr/local/install/php-4.0RC2 -I/usr/local/install/php-4.0RC2/Z
end -I/usr/local/install/php-4.0RC2/Zend -I/usr/local/install/php-4.0RC2 -DUSE_E
XPAT -I./lib/expat-lite -DNO_DL_NEEDED `./apaci`    \
      -o httpd buildmark.o modules.o modules/standard/libstandard.a modules/php4
/libphp4.a main/libmain.a ./os/unix/libos.a ap/libap.a  lib/expat-lite/libexpat.
a  -Wl,-rpath,/usr/local/mysql/lib/mysql  -rdynamic -L/usr/local/mysql/lib/mysql
 -Lmodules/php4 -L../modules/php4 -L../../modules/php4 -lmodphp4  -lgdbm  -ldl -
lmysqlclient -lgd -lresolv -lm -ldl -lcrypt -lnsl  -lresolv  -lm -lcrypt
modules/php4/libphp4.a(zend_operators.o): In function `is_numeric_string':
/usr/local/install/php-4.0RC2/Zend/zend_operators.c:1408: undefined reference to
 `isfinite'
collect2: ld returned 1 exit status
make[2]: *** [target_static] Error 1
make[2]: Leaving directory `/usr/local/install/apache_1.3.12/src'
make[1]: *** [build-std] Error 2
make[1]: Leaving directory `/usr/local/install/apache_1.3.12'
make: *** [build] Error 2