Update macOS version for build workflow (#678)

* Update macOS version for build workflow

Update to `macos-15-intel`. Note this is the last intel version before ARM64. See actions/runner-images#13046 for further details.

* Use std::vector instead of VLA for MIDI buffer

Replaced variable length array with std::vector for buffer.

Author: ryfactor

.github/workflows/build-osx-wizmode.yml

@@ -14,7 +14,7 @@ env:
 jobs:
   build:
     # custom libpng build fails a test on macos-latest (11.x)
-    runs-on: macos-13
+    runs-on: macos-15-intel
     steps:
       - uses: actions/checkout@v2
         with:

audio/RtMidi.cpp

@@ -1032,9 +1032,10 @@ void MidiOutCore :: sendMessage( std::vector<unsigned char> *message )
     return;
   }
 
-  Byte buffer[nBytes+(sizeof(MIDIPacketList))];
-  ByteCount listSize = sizeof(buffer);
-  MIDIPacketList *packetList = (MIDIPacketList*)buffer;
+  // Replace the buffer VLA with a std::vector-based buffer to avoid VLA.
+  std::vector<Byte> bufferVec(nBytes + sizeof(MIDIPacketList));
+  ByteCount listSize = static_cast<ByteCount>(bufferVec.size());
+  MIDIPacketList *packetList = reinterpret_cast<MIDIPacketList*>(bufferVec.data());
   MIDIPacket *packet = MIDIPacketListInit( packetList );
 
   ByteCount remainingBytes = nBytes;