patch 8.1.2077: the ops.c file is too big

Problem:    The ops.c file is too big.
Solution:   Move code for dealing with registers to a new file. (Yegappan
            Lakshmanan, closes #4982)
diff --git a/src/Make_vms.mms b/src/Make_vms.mms
index 6c791f1..b8e5085 100644
--- a/src/Make_vms.mms
+++ b/src/Make_vms.mms
@@ -319,7 +319,7 @@
 	memfile.c memline.c message.c misc1.c misc2.c mouse.c move.c normal.c \
 	ops.c \
 	option.c optionstr.c popupmnu.c popupwin.c profiler.c quickfix.c \
-	regexp.c scriptfile.c \
+	regexp.c register.c scriptfile.c \
 	search.c session.c sha256.c sign.c spell.c spellfile.c syntax.c tag.c \
 	term.c termlib.c testing.c textprop.c ui.c undo.c usercmd.c \
 	userfunc.c version.c viminfo.c screen.c window.c os_unix.c os_vms.c \
@@ -340,7 +340,7 @@
 	misc1.obj misc2.obj mouse.obj move.obj mbyte.obj normal.obj ops.obj \
 	option.obj \
 	optionstr.obj popupmnu.obj popupwin.obj profiler.obj quickfix.obj \
-	regexp.obj scriptfile.obj \
+	regexp.obj register.obj scriptfile.obj \
 	search.obj session.obj sha256.obj sign.obj spell.obj spellfile.obj \
 	syntax.obj tag.obj term.obj termlib.obj testing.obj textprop.obj \
 	ui.obj undo.obj usercmd.obj userfunc.obj screen.obj version.obj \
@@ -755,6 +755,10 @@
  ascii.h keymap.h term.h macros.h structs.h regexp.h \
  gui.h beval.h [.proto]gui_beval.pro option.h ex_cmds.h proto.h \
  globals.h
+register.obj : register.c vim.h [.auto]config.h feature.h os_unix.h \
+ ascii.h keymap.h term.h macros.h structs.h regexp.h \
+ gui.h beval.h [.proto]gui_beval.pro option.h ex_cmds.h proto.h \
+ globals.h
 scriptfile.obj : scriptfile.c vim.h [.auto]config.h feature.h os_unix.h \
  ascii.h keymap.h term.h macros.h structs.h regexp.h \
  gui.h beval.h [.proto]gui_beval.pro option.h ex_cmds.h proto.h \