tests: kdoc: fix warnings when new files are added

Use the git incantation we used for linters to avoid trying
to include new files in the "before" counts.

Signed-off-by: Jakub Kicinski <[email protected]>

Author: kuba-moo

tests/patch/kdoc/kdoc.sh

@@ -8,20 +8,21 @@ tmpfile_o=$(mktemp)
 tmpfile_n=$(mktemp)
 rc=0
 
-files=$(git diff HEAD^ --pretty= --name-only)
+files_mod=$(git show --diff-filter=M  --pretty="" --name-only "HEAD")
+files_all=$(git show --diff-filter=AM --pretty="" --name-only "HEAD")
 
 HEAD=$(git rev-parse HEAD)
 
 echo "Checking the tree before the patch"
 git checkout -q HEAD~
-./scripts/kernel-doc -Wall -none $files 2> >(tee $tmpfile_o >&2)
+./scripts/kernel-doc -Wall -none $files_mod 2> >(tee $tmpfile_o >&2)
 
 incumbent=$(grep -v 'Error: Cannot open file ' $tmpfile_o | wc -l)
 
 echo "Checking the tree with the patch"
 
 git checkout -q $HEAD
-./scripts/kernel-doc -Wall -none $files 2> >(tee $tmpfile_n >&2)
+./scripts/kernel-doc -Wall -none $files_all 2> >(tee $tmpfile_n >&2)
 
 current=$(grep -v 'Error: Cannot open file ' $tmpfile_n | wc -l)