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/mailmap.h b/mailmap.h
index ed7c93b..d0e6564 100644
--- a/mailmap.h
+++ b/mailmap.h
@@ -1,6 +1,8 @@
 #ifndef MAILMAP_H
 #define MAILMAP_H
 
+struct string_list;
+
 int read_mailmap(struct string_list *map, char **repo_abbrev);
 void clear_mailmap(struct string_list *map);