patch 8.1.1687: the evalfunc.c file is too big

Problem:    The evalfunc.c file is too big.
Solution:   Move testing support to a separate file.
diff --git a/src/Make_mvc.mak b/src/Make_mvc.mak
index 4a6aaa9..7ce8d3d 100644
--- a/src/Make_mvc.mak
+++ b/src/Make_mvc.mak
@@ -773,6 +773,7 @@
 	$(OUTDIR)\syntax.obj \
 	$(OUTDIR)\tag.obj \
 	$(OUTDIR)\term.obj \
+	$(OUTDIR)\testing.obj \
 	$(OUTDIR)\textprop.obj \
 	$(OUTDIR)\ui.obj \
 	$(OUTDIR)\undo.obj \
@@ -1620,6 +1621,8 @@
 
 $(OUTDIR)/term.obj:	$(OUTDIR) term.c  $(INCL)
 
+$(OUTDIR)/term.obj:	$(OUTDIR) testing.c  $(INCL)
+
 $(OUTDIR)/textprop.obj:	$(OUTDIR) textprop.c  $(INCL)
 
 $(OUTDIR)/ui.obj:	$(OUTDIR) ui.c  $(INCL)
@@ -1778,6 +1781,7 @@
 	proto/syntax.pro \
 	proto/tag.pro \
 	proto/term.pro \
+	proto/testing.pro \
 	proto/textprop.pro \
 	proto/ui.pro \
 	proto/undo.pro \