Enabled AltRef motion map creation

Enabled the first-pass encode to output the
map of macroblock coding modes required by
the AltRef filter.
diff --git a/vp8/encoder/firstpass.c b/vp8/encoder/firstpass.c
index 684ad9b..0a6e8c5 100644
--- a/vp8/encoder/firstpass.c
+++ b/vp8/encoder/firstpass.c
@@ -30,7 +30,7 @@
 #include "encodemv.h"
 
 //#define OUTPUT_FPF 1
-//#define FIRSTPASS_MM 1
+#define FIRSTPASS_MM 1
 
 #if CONFIG_RUNTIME_CPU_DETECT
 #define IF_RTCD(x) (x)