While pdo-odbc indeed needs either unixODBC or ibm-db2, we're not building that extension anyway. odbc extension, on the other hand, can use libiodbc, but for some reason, iodbc useflag forces unixODBC dep - I don't see any reason for it, it build fine without it (though I think I needed to make one other correction in eclass, except the dep). I would also want to repeat my question about the use of '--host=${CHOST}' by configure, perhaps there was a historical reason for it, but now, it seems to cause only a configure warning and builds fine without it. On a semi-related note: libiodbc-3.52.7 has been released a few days ago - it seems just minor fixes, old ebuild works (yeah, probably I should open a separate bug about this).
Looking at portage sources, it seems that the simplest solution of 'host' warning would be adding '${CBUILD:+--build=${CBUILD}}' to configure parameters, just as portage does for econf (if I read them correctly, CBUILD is always set anyway, either explicitly, or equal to CHOST).
All the work is going into the php-5.3.2 ebuild, wnich has the correct iodbc deps and does not use the --host configure parameter anymore. I don't have plans to fix php5_2-sapi.eclass, as we focus all of the energy on getting php-5.3 ready and these issues are not critical. Nevertheless, thanks for pointing them out.
