vp8cx : bestsad declared and initialized incorrectly.

bestsad should be an int initialized to INT_MAX.  The optimized
SAD function expects a signed value for bestsad to use for comparison
and early loop termination.  When no match is made, which is
determined by a comparison of bestsad to INT_MAX, INT_MAX is returned.

vp8/encoder/mcomp.c

diff --git a/vp8/encoder/mcomp.c b/vp8/encoder/mcomp.c
index 4c3edd7..6d69a9e 100644
--- a/vp8/encoder/mcomp.c
+++ b/vp8/encoder/mcomp.c
@@ -997,7 +997,7 @@
     int tot_steps;
     MV this_mv;
 
-    unsigned int bestsad = UINT_MAX;
+    int bestsad = INT_MAX;
     int best_site = 0;
     int last_site = 0;