Ignore REAPER host function API requests

Apparently there is a plugin that uses these.

CHANGELOG.md

@@ -26,6 +26,10 @@ Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### Fixed
 
+- Fixed _Insert Piz Here_'s _midiLooper_ crashing in **REAPER** when the plugin
+  tries to use REAPER's [host function
+  API](https://www.reaper.fm/sdk/vst/vst_ext.php#vst_host) which currently isn't
+  supported by yabridge. We now explicitly ignore these requests.
 - Fixed VST2 speaker arrangement configurations returned by the plugin not being
   serialized correctly. No plugins seem to actually use these, so it should not
   have caused any issues.

src/common/logging/vst2.cpp

@@ -322,6 +322,9 @@ std::optional<std::string> opcode_to_string(bool is_dispatch, int opcode) {
             case audioMasterGetInputSpeakerArrangement:
                 return "audioMasterGetInputSpeakerArrangement";
                 break;
+            case audioMasterDeadBeef:
+                return "0xdeadbeef";
+                break;
             default:
                 return std::nullopt;
                 break;

src/common/vst24.h

@@ -89,6 +89,15 @@
  */
 [[maybe_unused]] constexpr int kVstProcessPrecision32 = 0;
 
+/**
+ * Used by VST2 plugins in REAPER to obtain pointers to host-specific functions
+ * implemented by REAPER.
+ *
+ * https://www.reaper.fm/sdk/vst/vst_ext.php#vst_host
+ */
+[[maybe_unused]] constexpr int audioMasterDeadBeef =
+    static_cast<int>(0xdeadbeef);
+
 /**
  * The struct that's being passed through the data parameter during the
  * `effGetInputProperties` and `effGetOutputProperties` opcodes. Reverse

src/plugin/bridges/vst2.cpp

@@ -147,6 +147,20 @@ Vst2PluginBridge::Vst2PluginBridge(audioMasterCallback host_callback)
                                 .value_payload = std::nullopt};
                         }
                     } break;
+                    case audioMasterDeadBeef:
+                        logger.log("");
+                        logger.log(
+                            "   The plugin wants to use REAPER's host vendor "
+                            "extensions");
+                        logger.log(
+                            "   which currently aren't supported by yabridge.");
+                        logger.log("   Ignoring the request.");
+                        logger.log("");
+
+                        return Vst2EventResult{.return_value = 0,
+                                               .payload = nullptr,
+                                               .value_payload = std::nullopt};
+                        break;
                 }
 
                 return passthrough_event(&plugin, host_callback_function,

src/wine-host/bridges/vst2.cpp

@@ -554,6 +554,9 @@ class HostCallbackDataConverter : public DefaultDataConverter {
             case audioMasterUpdateDisplay:
             case audioMasterBeginEdit:
             case audioMasterEndEdit:
+            // NOTE: REAPER abuses the dispatcher to add their own opcodes
+            //       outside of `audioMasterVendorSpecific`
+            case audioMasterDeadBeef:
                 return nullptr;
                 break;
             default: