Add missing includes and forward declarations

I looped over the toplevel header files, creating a temporary two-line C
program for each consisting of
  #include "git-compat-util.h"
  #include $HEADER
This patch is the result of manually fixing errors in compiling those
tiny programs.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/bisect.h b/bisect.h
index a5d9248a47..34df209351 100644
--- a/bisect.h
+++ b/bisect.h
@@ -1,6 +1,8 @@
 #ifndef BISECT_H
 #define BISECT_H
 
+struct commit_list;
+
 /*
  * Find bisection. If something is found, `reaches` will be the number of
  * commits that the best commit reaches. `all` will be the count of