php: Look for libraries in ${baselib} rather than lib

It fails to look for libraries when we use lib64 for baselib,
use --with-libdir option to specify the correct directory.

$ ./configure --help|grep '\-\-with-libdir'
 --with-libdir=NAME      Look for libraries in .../NAME rather than .../lib

Signed-off-by: Jackie Huang <jackie.huang@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>