treewide: be explicit about dependence on advice.h

Dozens of files made use of advice functions, without explicitly
including advice.h.  This made it more difficult to find which files
could remove a dependence on cache.h.  Make C files explicitly include
advice.h if they are using it.

Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/commit.c b/builtin/commit.c
index 9d8e1ea..b09017e 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -7,6 +7,7 @@
 
 #define USE_THE_INDEX_VARIABLE
 #include "cache.h"
+#include "advice.h"
 #include "config.h"
 #include "lockfile.h"
 #include "cache-tree.h"