Fix an AHDRSSC release stage bug

In 8196b9a I optimized the AHDSR
to not generate the full block if not needed. This broke the
release stage. In SC we only saw this in EG2 which is why it lingered.
Anyway fix that.

include/sst/basic-blocks/modulators/AHDSRShapedSC.h

@@ -202,7 +202,14 @@ struct AHDSRShapedSC : DiscreteStagesEnvelope<BLOCK_SIZE, RangeProvider>
             else
             {
                 stage = base_t::s_release;
-                releaseStartValue = this->outputCache[0];
+                if (needsCurve)
+                {
+                    releaseStartValue = this->outputCache[0];
+                }
+                else
+                {
+                    releaseStartValue = this->outBlock0;
+                }
                 phase = 0;
             }
         }