scripts/checkpatch: roll diff tweaking into checkpatch itself

Rather than relying on external tweaks lets just do it inside
checkpatch's direct commitish handling which is QEMU specific code
anyway.

Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Willian Rampazzo <willianr@redhat.com>
Reviewed-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
Message-Id: <20210623102749.25686-4-alex.bennee@linaro.org>

scripts/checkpatch.pl

@@ -399,7 +399,12 @@ if ($chk_branch) {
 	my $num_patches = @patches;
 	for my $hash (@patches) {
 		my $FILE;
-		open($FILE, '-|', "git", "show", "--patch-with-stat", $hash) ||
+		open($FILE, '-|', "git",
+                     "-c", "diff.renamelimit=0",
+                     "-c", "diff.renames=True",
+                     "-c", "diff.algorithm=histogram",
+                     "show",
+                     "--patch-with-stat", $hash) ||
 			die "$P: git show $hash - $!\n";
 		while (<$FILE>) {
 			chomp;