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/trailer.h b/trailer.h
index 6d7f8c2a5..9c10026c3 100644
--- a/trailer.h
+++ b/trailer.h
@@ -3,6 +3,8 @@
 
 #include "list.h"
 
+struct strbuf;
+
 enum trailer_where {
 	WHERE_DEFAULT,
 	WHERE_END,