Fixed gcc 4 build.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@15010 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/os/midi/MidiSynth.h

@@ -7,6 +7,8 @@
 #include <Synth.h>
 #include <MidiDefs.h>
 
+class BSynth;
+
 class BMidiSynth : public BMidi
 {
 public:

headers/os/midi/Synth.h

@@ -87,8 +87,8 @@ public:
 
 private:
 
-	friend BMidiSynth;
-	friend BMidiSynthFile;
+	friend class BMidiSynth;
+	friend class BMidiSynthFile;
 
 	virtual void _ReservedSynth1();
 	virtual void _ReservedSynth2();