Since the OpenWrt's stub libiconv implementation is now gone,
we can build against musl's internal one or the external libiconv
implementation.
This needs minor adjustements in the makefile to allow PHPs build
to choose the right path when cross-compiling.
Signed-off-by: Michael Heimpold <mhei@heimpold.de>
Active support for PHP 7.4 branch ended a few days ago.
Since we have PHP 8.x in the repository for a while
and we migrated all PECL extension packages already,
let's focus on that newer version and drop support for 7.4.
Signed-off-by: Michael Heimpold <mhei@heimpold.de>