audio/bambootracker: Mark broken

The port is incompatible with rtaudio 6.x. The port broke after the
recent audio/rtaudio update.

The issue is known upstream and is being tracked under:

BambooTracker/BambooTracker#492

Mark port broken while either an upstream fix or workaround is found.

Notified by:	pkg-fallout

audio/bambootracker/Makefile

@@ -10,6 +10,9 @@ MAINTAINER=	ehaupt@FreeBSD.org
 COMMENT=	Music tracker for the Yamaha YM2608 (OPNA) sound chip
 WWW=		https://github.com/rerrahkr/BambooTracker
 
+# https://github.com/BambooTracker/BambooTracker/issues/492
+BROKEN=		incompatible with rtaudio 6.x
+
 LICENSE=	GPLv2
 LICENSE_FILE=	${WRKSRC}/LICENSE