patch 8.2.3860: Vim9: codecov struggles with the file size

Problem:    Vim9: codecov struggles with the file size.
Solution:   Split vim9compile.c into four files.
diff --git a/src/Make_ami.mak b/src/Make_ami.mak
index 12f7fe5..dd674dc 100644
--- a/src/Make_ami.mak
+++ b/src/Make_ami.mak
@@ -180,8 +180,11 @@
 	userfunc.c \
 	version.c \
 	viminfo.c \
+	vim9cmds.c \
 	vim9compile.c \
 	vim9execute.c \
+	vim9expr.c \
+	vim9instr.c \
 	vim9script.c \
 	vim9type.c \
 	window.c \