[3.10] Mark all clinic headers as generated (GH-30679). (GH-30726)

(cherry picked from commit 71734d0)

Co-authored-by: Erlend Egeberg Aasland <erlend.aasland@innova.no>

.gitattributes

@@ -40,11 +40,8 @@ PCbuild/readme.txt text eol=crlf
 PC/readme.txt text eol=crlf
 
 # Generated files
-# https://github.com/github/linguist#generated-code
-Modules/clinic/*.h          linguist-generated=true
-Objects/clinic/*.h          linguist-generated=true
-PC/clinic/*.h               linguist-generated=true
-Python/clinic/*.h           linguist-generated=true
+# https://github.com/github/linguist/blob/master/docs/overrides.md
+**/clinic/*.h               linguist-generated=true
 Python/importlib.h          linguist-generated=true
 Python/importlib_external.h linguist-generated=true
 Include/internal/pycore_ast.h   linguist-generated=true