- handled the final piece where Timidity++ had a direct dependency on GZDoom - the error logging function.

This is npw a function pointer so that a simple stdout printout can be used as default, but allows to override it.
Also added the missing timidity_file.h header.

src/sound/timiditypp/common.cpp

@@ -27,6 +27,7 @@
 #include <string.h>
 #include <ctype.h>
 #include "common.h"
+#include "controls.h"
 
 namespace TimidityPlus
 {
@@ -151,5 +152,31 @@ int tf_getc(struct timidity_file *tf)
 	return read == 0 ? EOF : c;
 }
 
+void default_ctl_cmsg(int type, int verbosity_level, const char* fmt, ...)
+{
+	if (verbosity_level >= VERB_DEBUG) return;	// Don't waste time on diagnostics.
+
+	char buffer[2048];
+	va_list args;
+	va_start(args, fmt);
+
+	switch (type)
+	{
+	case CMSG_ERROR:
+		vprintf("Error: %s\n", args);
+		break;
+
+	case CMSG_WARNING:
+		vprintf("Warning: %s\n", args);
+		break;
+
+	case CMSG_INFO:
+		vprintf("Info: %s\n", args);
+		break;
+	}
+}
+
+// Allow hosting applications to capture the messages and deal with them themselves.
+void (*ctl_cmsg)(int type, int verbosity_level, const char* fmt, ...) = default_ctl_cmsg;
 
 }