bpo-40328: Add tool for generating cjk mapping headers (GH-19602)

diff --git a/Modules/cjkcodecs/README b/Modules/cjkcodecs/README
index 8f08f2d..165ae7a 100644
--- a/Modules/cjkcodecs/README
+++ b/Modules/cjkcodecs/README
@@ -1,8 +1,6 @@
 To generate or modify mapping headers
 -------------------------------------
-Mapping headers are imported from CJKCodecs as pre-generated form.
-If you need to tweak or add something on it, please look at tools/
-subdirectory of CJKCodecs' distribution.
+Mapping headers are generated from Tools/unicode/genmap_*.py
 
 
 
diff --git a/Modules/cjkcodecs/mappings_cn.h b/Modules/cjkcodecs/mappings_cn.h
index 1f8c299..87ca0de 100644
--- a/Modules/cjkcodecs/mappings_cn.h
+++ b/Modules/cjkcodecs/mappings_cn.h
@@ -1,3 +1,4 @@
+// AUTO-GENERATED FILE FROM genmap_schinese.py: DO NOT EDIT
 static const ucs2_t __gb2312_decmap[7482] = {
 12288,12289,12290,12539,713,711,168,12291,12293,8213,65374,8214,8230,8216,
 8217,8220,8221,12308,12309,12296,12297,12298,12299,12300,12301,12302,12303,
diff --git a/Modules/cjkcodecs/mappings_jisx0213_pair.h b/Modules/cjkcodecs/mappings_jisx0213_pair.h
index 729e4bc..c96f201 100644
--- a/Modules/cjkcodecs/mappings_jisx0213_pair.h
+++ b/Modules/cjkcodecs/mappings_jisx0213_pair.h
@@ -1,3 +1,4 @@
+// AUTO-GENERATED FILE FROM genmap_japanese.py: DO NOT EDIT
 #define JISX0213_ENCPAIRS 46
 #ifdef EXTERN_JISX0213_PAIR
 static const struct widedbcs_index *jisx0213_pair_decmap;
diff --git a/Modules/cjkcodecs/mappings_jp.h b/Modules/cjkcodecs/mappings_jp.h
index c6dae3d..409aeae 100644
--- a/Modules/cjkcodecs/mappings_jp.h
+++ b/Modules/cjkcodecs/mappings_jp.h
@@ -1,3 +1,4 @@
+// AUTO-GENERATED FILE FROM genmap_japanese.py: DO NOT EDIT
 static const ucs2_t __jisx0208_decmap[6956] = {
 12288,12289,12290,65292,65294,12539,65306,65307,65311,65281,12443,12444,180,
 65344,168,65342,65507,65343,12541,12542,12445,12446,12291,20189,12293,12294,
diff --git a/Modules/cjkcodecs/mappings_kr.h b/Modules/cjkcodecs/mappings_kr.h
index 7e6fdd2..bb59acc 100644
--- a/Modules/cjkcodecs/mappings_kr.h
+++ b/Modules/cjkcodecs/mappings_kr.h
@@ -1,3 +1,4 @@
+// AUTO-GENERATED FILE FROM genmap_korean.py: DO NOT EDIT
 static const ucs2_t __ksx1001_decmap[8264] = {
 12288,12289,12290,183,8229,8230,168,12291,173,8213,8741,65340,8764,8216,8217,
 8220,8221,12308,12309,12296,12297,12298,12299,12300,12301,12302,12303,12304,
@@ -3249,3 +3250,4 @@
 __cp949_encmap+32891,0,11},{0,0,0},{0,0,0},{0,0,0},{0,0,0},{__cp949_encmap+
 32903,1,230},
 };
+