Move firstpass motion map to stats packet

The first implementation of the firstpass motion map for motion
compensated temporal filtering created a file, fpmotionmap.stt,
in the current working directory. This was not safe for multiple
encoder instances. This patch merges this data into the first pass
stats packet interface, so that it is handled like the other
(numerical) firstpass stats.

The new stats packet is defined as follows:
    Numerical Stats (16 doubles) -- 128 bytes
    Motion Map                   -- 1 byte / Macroblock
    Padding                      -- to align packet to 8 bytes

The fpmotionmap.stt file can still be generated for debugging
purposes in the same way that the textual version of the stats
are available (defining OUTPUT_FPF in firstpass.c)

Change-Id: I083ffbfd95e7d6a42bb4039ba0e81f678c8183ca
diff --git a/vp8/encoder/onyx_int.h b/vp8/encoder/onyx_int.h
index 8a34a1f..51b62c6 100644
--- a/vp8/encoder/onyx_int.h
+++ b/vp8/encoder/onyx_int.h
@@ -461,14 +461,14 @@
 
     int target_bandwidth;
     long long bits_left;
-    FIRSTPASS_STATS total_stats;
-    FIRSTPASS_STATS this_frame_stats;
+    FIRSTPASS_STATS *total_stats;
+    FIRSTPASS_STATS *this_frame_stats;
     FIRSTPASS_STATS *stats_in, *stats_in_end;
     struct vpx_codec_pkt_list  *output_pkt_list;
     int                          first_pass_done;
     unsigned char *fp_motion_map;
-    FILE *fp_motion_mapfile;
-    int fpmm_pos;
+
+    unsigned char *fp_motion_map_stats, *fp_motion_map_stats_save;
 
 #if 0
     // Experimental code for lagged and one pass