Add git-diff orderFile

It's helpful to have a common order of file types in patches.
Applying git-diff's orderFile feature allows us to do that. Just
do 'git config diff.orderFile scripts/git.difforder' to enable it.
Acked-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

README.md

@@ -79,3 +79,9 @@ You can add the following to .git/config to do this automatically for you:
     [format]
         subjectprefix = kvm-unit-tests PATCH
 
+Additionally it's helpful to have a common order of file types in patches.
+Our chosen order attempts to place the more declarative files before
+the code files. We also start with common code and finish with unit test
+code. git-diff's orderFile feature allows us to specify the order in a
+file. The orderFile we use is `scripts/git.difforder`. Adding the config
+with `git config diff.orderFile scripts/git.difforder` enables it.

scripts/git.difforder

+COPYRIGHT
+MAINTAINERS
+*README
+scripts/*.mak
+scripts/*.py
+scripts/*.bash
+scripts/*.sh
+scripts/*
+*/run
+run_tests.sh
+configure
+*Makefile*
+*.mak
+lib/*.lds
+lib/linux/*
+lib/asm-generic/*
+lib/*/asm/*
+lib/*.h
+lib/*.S
+lib/*.c
+*.lds
+*.h
+*.S
+*.c
+*.cfg