treewide: remove unnecessary git-compat-util.h includes in headers

For sanity, we should probably do one of the following:

(a) make C and header files both depend upon everything they need
(b) consistently exclude git-compat-util.h from headers and require it
    be the first include in C files

Currently, we have some of the headers following (a) and others
following (b), which makes things messy.  In the past I was pushed
towards (b), as per [1] and [2].  Further, during this series I
discovered that this mixture empirically will mean that we end up with C
files that do not directly include git-compat-util.h, and do include
headers that don't include git-compat-util.h, with the result that we
likely have headers included before an indirect inclusion of
git-compat-util.h.  Since git-compat-util.h has tricky platform-specific
stuff that is meant to be included before everything else, this state of
affairs is risky and may lead to things breaking in subtle ways (and
only on some platforms) as per [1] and [2].

Since including git-compat-util.h in existing header files makes it
harder for us to catch C files that are missing that include, let's
switch to (b) to make the enforcement of this rule easier.  Remove the
inclusion of git-compat-util.h from header files other than the ones
that have been approved as alternate first includes.

[1] https://lore.kernel.org/git/20180811173406.GA9119@sigill.intra.peff.net/
[2] https://lore.kernel.org/git/20180811174301.GA9287@sigill.intra.peff.net/

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

advice.h

@@ -1,8 +1,6 @@
 #ifndef ADVICE_H
 #define ADVICE_H
 
-#include "git-compat-util.h"
-
 struct string_list;
 
 /*

cbtree.h

@@ -14,8 +14,6 @@
 #ifndef CBTREE_H
 #define CBTREE_H
 
-#include "git-compat-util.h"
-
 struct cb_node;
 struct cb_node {
 	struct cb_node *child[2];

chunk-format.h

@@ -1,7 +1,6 @@
 #ifndef CHUNK_FORMAT_H
 #define CHUNK_FORMAT_H
 
-#include "git-compat-util.h"
 #include "hash.h"
 
 struct hashfile;

commit-graph.h

@@ -1,7 +1,6 @@
 #ifndef COMMIT_GRAPH_H
 #define COMMIT_GRAPH_H
 
-#include "git-compat-util.h"
 #include "object-store.h"
 #include "oidset.h"
 

commit-slab-impl.h

@@ -1,8 +1,6 @@
 #ifndef COMMIT_SLAB_IMPL_H
 #define COMMIT_SLAB_IMPL_H
 
-#include "git-compat-util.h"
-
 #define implement_static_commit_slab(slabname, elemtype) \
 	implement_commit_slab(slabname, elemtype, MAYBE_UNUSED static)
 

hash.h

@@ -1,7 +1,6 @@
 #ifndef HASH_H
 #define HASH_H
 
-#include "git-compat-util.h"
 #include "repository.h"
 
 #if defined(SHA1_APPLE)

pack-mtimes.h

@@ -1,8 +1,6 @@
 #ifndef PACK_MTIMES_H
 #define PACK_MTIMES_H
 
-#include "git-compat-util.h"
-
 #define MTIMES_SIGNATURE 0x4d544d45 /* "MTME" */
 #define MTIMES_VERSION 1
 

pkt-line.h

@@ -1,7 +1,6 @@
 #ifndef PKTLINE_H
 #define PKTLINE_H
 
-#include "git-compat-util.h"
 #include "strbuf.h"
 #include "sideband.h"
 

repository.h

@@ -1,7 +1,6 @@
 #ifndef REPOSITORY_H
 #define REPOSITORY_H
 
-#include "git-compat-util.h"
 #include "path.h"
 
 struct config_set;

sub-process.h

@@ -1,7 +1,6 @@
 #ifndef SUBPROCESS_H
 #define SUBPROCESS_H
 
-#include "git-compat-util.h"
 #include "hashmap.h"
 #include "run-command.h"
 

trace.h

@@ -1,7 +1,6 @@
 #ifndef TRACE_H
 #define TRACE_H
 
-#include "git-compat-util.h"
 #include "strbuf.h"
 
 /**