patch 8.2.4252: generating the normal command table at runtime is inefficient

Problem:    Generating the normal command table at runtime is inefficient.
Solution:   Generate the table with a Vim script and put it in a header file.
            (Yegappan Lakshmanan, closes #9648)
diff --git a/src/Makefile b/src/Makefile
index cdb491b..549b817 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -2144,6 +2144,16 @@
 cmdidxs: ex_cmds.h
 	vim --clean -X --not-a-term -u create_cmdidxs.vim
 
+# Run vim script to generate the normal/visual mode command lookup table.
+# This only needs to be run when a new normal/visual mode command has been
+# added.  If this fails because you don't have Vim yet:
+#   - change nv_cmds[] in normal.c to add the new normal/visual mode command.
+#   - build Vim
+#   - run "make nvcmdidxs" using the new Vim to generate nv_cmdidxs.h
+#   - rebuild Vim to use the newly generated nv_cmdidxs.h file.
+nvcmdidxs: normal.c
+	./$(VIMTARGET) --clean -X --not-a-term -u create_nvcmdidxs.vim
+
 
 # The normal command to compile a .c file to its .o file.
 # Without or with ALL_CFLAGS.
@@ -4002,7 +4012,7 @@
 objects/normal.o: normal.c vim.h protodef.h auto/config.h feature.h os_unix.h \
  auto/osdef.h ascii.h keymap.h termdefs.h macros.h option.h beval.h \
  proto/gui_beval.pro structs.h regexp.h gui.h alloc.h ex_cmds.h spell.h \
- proto.h globals.h errors.h
+ proto.h globals.h errors.h nv_cmdidxs.h
 objects/ops.o: ops.c vim.h protodef.h auto/config.h feature.h os_unix.h \
  auto/osdef.h ascii.h keymap.h termdefs.h macros.h option.h beval.h \
  proto/gui_beval.pro structs.h regexp.h gui.h alloc.h ex_cmds.h spell.h \