why does specifying EXTENSION_DIR for i586 & x86_64 arch's behave differently? how to fix?

i'm building php 5.4 from svn sources on opensuse 12.1, x86_64 & i686
arches

using identical upstream sources, and a vanilla './configure',

case (1): i686
	uname -rmpio
		3.1.9-1.4-default i686 i686 i386 GNU/Linux
	cd php5
	svn info | head -n 5
		Path: .
		URL:
		https://svn.php.net/repository/php/php-src/branches/PHP_5_4
		Repository Root: https://svn.php.net/repository
		Repository UUID: c90b9560-bf6c-de11-be94-00142212c4b1
		Revision: 324163
	./buildconf
	./configure --prefix=/usr/local/php5 --with-libdir=lib

case (2): x86_64
	uname -rmpio
		3.1.9-1.4-default x86_64 x86_64 x86_64 GNU/Linux
	cd php5
	svn info | head -n 5
		Path: .
		URL:
		https://svn.php.net/repository/php/php-src/branches/PHP_5_4
		Repository Root: https://svn.php.net/repository
		Repository UUID: c90b9560-bf6c-de11-be94-00142212c4b1
		Revision: 324163
	./buildconf
	./configure --prefix=/usr/local/php5 --with-libdir=lib64

a quick check of the derived EXTENSION_DIR,

	grep "EXTENSION_DIR =" Makefile

returns

	(1) EXTENSION_DIR =
	/usr/local/php5/lib/php/extensions/no-debug-non-zts-20100525
	(2) EXTENSION_DIR =
	/usr/local/php5/lib64/extensions/no-debug-non-zts-20100525

note the difference,

	(1) EXTENSION_DIR = .../lib/php/extensions...
	(2) EXTENSION_DIR = .../lib64/extensions/...

why does the i686-case add the extra '/php/' to the path?

what i'd expected/intended was to have:

	(1) EXTENSION_DIR = .../lib/extensions...
	(2) EXTENSION_DIR = .../lib64/extensions/...

how do i get there?

locuse