[CentOS] Error rebuilding PHP5 under CentOS 5

First off, I apologize if this is off-topic.
 
I'm sending it to the CentOS list because I would have to believe this is a
configuration issue of the packages CentOS/upstream are providing.  In any
case, I have to start somewhere. 
 
While re-building PHP5 under CentOS5 (to enable Oracle functions via the
--with-oci8 option), I receive a compile error while compiling cast.c
because the cookie_io_functions_t type is not found.
 
To resolve the issue, I added the -D_GNU_SOURCE option to DEFS in the
makefile and (I think this is redundant but I didn't have enough time to go
through the configuration options) I add: " #include <libio.h> "in the
php_config.h file
 
Gut feeling is that I should not have to change the source code and a
combination of -D options in makefile should resolve this.  If this is a
source code issue, then I'm surprised.  
 
OK.  After I did these changes, I was able to successfully build PHP5 using
the php-5.1.6-5.el5.src.rpm source rpm of the original package for CentOS5
but not the latest php-5.1.6-12.el5.src.rpm source rpm found in updates.

I used to build PHP5 under CentOS 4 without having to change source or -D
options (using PHP 5 in CentOSPlus) and it worked fine.

MY QUESTION:
-------------

Is this a configuration issue or should I be reporting this to the php list?

-------------

Again, I've done this under CentOS4 with no problems whatsoever.

Here are the steps I took:

- Downloaded source rpm
- Applied all patches
- ran autoconf -f
- ran configure with the --with-oci8 option and all the options that apache
was compiled with in CentOS5 (obtained them by running phpinfo() in a php
script).
- make
 
Thanks,
Michael