Fix typo:

include/plugin.h:1005:20: error: no member named 'opaddr' in 'InPlug<N>'; did you mean 'opadr'?

https://bugs.gentoo.org/938333
https://codeberg.org/gentoo/gentoo/src/branch/master/media-sound/csound/files/csound-6.17.0-typo-instantiate.patch
--- include/plugin.h.orig
+++ include/plugin.h
@@ -1002,7 +1002,7 @@ template <std::size_t N> struct InPlug : OPDS {
   /** check if this opcode runs at perf time
   */
   bool is_perf() {
-      return this->opaddr ? true : false;
+      return this->opadr ? true : false;
   }
 
 };