audio/ladspa: Fix fetch

The content is identical with https://distfiles.gentoo.org/distfiles/17/ladspa_sdk_1.17.tgz (71,052 bytes, d9d596171d93f9c226fcdb7e27c6f917422ac487efe2c05e0a18094df4268061).

% make fetch

> License LGPL21 accepted by the user

> ladspa_sdk_1.17.tgz doesn't seem to exist in /usr/ports/distfiles/.

> Attempting to fetch http://www.ladspa.org/download/ladspa_sdk_1.17.tgz

fetch: http://www.ladspa.org/download/ladspa_sdk_1.17.tgz: size mismatch: expected 71052, actual 71053

> Attempting to fetch http://distcache.FreeBSD.org/ports-distfiles/ladspa_sdk_1.17.tgz

fetch: http://distcache.FreeBSD.org/ports-distfiles/ladspa_sdk_1.17.tgz: Not Found

> Couldn't fetch it - please try to retrieve this

> port manually into /usr/ports/distfiles/ and try again.

• Error code 1

Stop.
make: stopped in /usr/ports/audio/ladspa

(cherry picked from commit dc07de1ab5036521db211ed806e18ad7b750cc3e)