blame and friends: adjust to multiple pathspec change.

This makes things that include revision.h build again.

Blame is also built, but I am not sure how well it works (or how
well it worked to begin with) -- it was relying on tree-diff to
be using whatever pathspec was used the last time, which smells
a bit suspicious.

Signed-off-by: Junio C Hamano <junkio@cox.net>

rev-list.c

@@ -5,6 +5,7 @@
 #include "tree.h"
 #include "blob.h"
 #include "tree-walk.h"
+#include "diff.h"
 #include "revision.h"
 
 /* bits #0-6 in revision.h */