Make run faster on ARM CPUs using fast math approximation

Use --fast-math to use sine/cosine tables and approximate atan2.

src/bnetz/main.c

@@ -176,7 +176,8 @@ int main(int argc, char *argv[])
 	if (!loopback)
 		print_image();
 
-	/* init functions */
+	/* inits */
+	fm_init(fast_math);
 	dsp_init();
 	bnetz_init();
 
@@ -204,6 +205,9 @@ fail:
 	while(sender_head)
 		bnetz_destroy(sender_head);
 
+	/* exits */
+	fm_exit();
+
 	return 0;
 }