Try fixing a null termination bug in ma_channel_map_to_string().

Public issue https://github.com/mackron/miniaudio/issues/980

miniaudio.h

@@ -56458,8 +56458,12 @@ MA_API size_t ma_channel_map_to_string(const ma_channel* pChannelMap, ma_uint32
     }
 
     /* Null terminate. Don't increment the length here. */
-    if (pBufferOut != NULL && bufferCap > len + 1) {
-        pBufferOut[len] = '\0';
+    if (pBufferOut != NULL) {
+        if (bufferCap > len) {
+            pBufferOut[len] = '\0';
+        } else if (bufferCap > 0) {
+            pBufferOut[bufferCap - 1] = '\0';
+        }
     }
 
     return len;