Include sha1.h from sha.c: It contains several prototypes.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@22099 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavutil/sha.c

@@ -25,6 +25,7 @@
 #include "avutil.h"
 #include "bswap.h"
 #include "sha.h"
+#include "sha1.h"
 #include "intreadwrite.h"
 
 /** hash context */