Attempt to fix trace-malloc bustage in libxul builds by removing LIBXUL_LIBRARY=1 (fixing tinderbox bustage for newly-enabled test).

tools/trace-malloc/lib/Makefile.in

@@ -46,7 +46,6 @@ MODULE		= tracemalloc
 LIBRARY_NAME	= tracemalloc
 EXPORT_LIBRARY	= 1
 DEFFILE		= $(win_srcdir)/tm.def
-LIBXUL_LIBRARY	= 1
 
 REQUIRES	= xpcom