Stop using deprecated dlopen() constructors

As I re-discovered for the third time last evening, LADSPA programmers still haven’t made the switch from _init() to __attribute__((constructor)) void init() {}.

The older mechanism has been deprecated since the early/mid ’90s. Most operating systems still supported it but with MacOSX 10.4, Apple dropped support when they implemented their own dlopen() support.

I’ve sent an email about it to the LAD mailing list, but apparently no one listened.