Hi,
On a debian server, updated from Debian 9 to 10, 11 and eventually 12, your solution works for exim, but not for php 8.
libtool: link: cannot find the library `/usr/local/lib/libiconv.la' or unhandled argument `/usr/local/lib/libiconv.la'
make: *** [Makefile:314 : sapi/cli/php] Erreur 1...