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_cyg_ming.mak b/src/Make_cyg_ming.mak
index fe04cb5..d9a50d2 100644
--- a/src/Make_cyg_ming.mak
+++ b/src/Make_cyg_ming.mak
@@ -825,8 +825,11 @@
 	$(OUTDIR)/usercmd.o \
 	$(OUTDIR)/userfunc.o \
 	$(OUTDIR)/version.o \
+	$(OUTDIR)/vim9cmds.o \
 	$(OUTDIR)/vim9compile.o \
 	$(OUTDIR)/vim9execute.o \
+	$(OUTDIR)/vim9expr.o \
+	$(OUTDIR)/vim9instr.o \
 	$(OUTDIR)/vim9script.o \
 	$(OUTDIR)/vim9type.o \
 	$(OUTDIR)/viminfo.o \
@@ -1203,10 +1206,16 @@
 
 $(OUTDIR)/version.o: version.c $(INCL) version.h
 
+$(OUTDIR)/vim9cmds.o: vim9cmds.c $(INCL) version.h
+
 $(OUTDIR)/vim9compile.o: vim9compile.c $(INCL) version.h
 
 $(OUTDIR)/vim9execute.o: vim9execute.c $(INCL) version.h
 
+$(OUTDIR)/vim9expr.o: vim9expr.c $(INCL) version.h
+
+$(OUTDIR)/vim9instr.o: vim9instr.c $(INCL) version.h
+
 $(OUTDIR)/vim9script.o: vim9script.c $(INCL) version.h
 
 $(OUTDIR)/vim9type.o: vim9type.c $(INCL) version.h