coq_makefile: Properly delay variable expansion in combined glob/vo rule

Fix coq#18076

tools/CoqMakefile.in

@@ -816,12 +816,12 @@ ifneq (,$(filter grouped-target,$(.FEATURES)))
 define globvorule=
 
 # take care to $$ variables using $< etc
-  $(1).vo $(1).glob &: $(1).v | $(VDFILE)
-	$(SHOW)COQC $(1).v
-	$(HIDE)$$(TIMER) $(COQC) $(COQDEBUG) $$(TIMING_ARG) $$(PROFILE_ARG) $(COQFLAGS) $(COQLIBS) $(1).v
+  $(1).vo $(1).glob &: $(1).v | $$(VDFILE)
+	$$(SHOW)COQC $(1).v
+	$$(HIDE)$$(TIMER) $$(COQC) $$(COQDEBUG) $$(TIMING_ARG) $$(PROFILE_ARG) $$(COQFLAGS) $$(COQLIBS) $(1).v
 ifeq ($(COQDONATIVE), "yes")
-	$(SHOW)COQNATIVE $(1).vo
-	$(HIDE)$(call TIMER,$(1).vo.native) $(COQNATIVE) $(COQLIBS) $(1).vo
+	$$(SHOW)COQNATIVE $(1).vo
+	$$(HIDE)$$(call TIMER,$(1).vo.native) $$(COQNATIVE) $$(COQLIBS) $(1).vo
 endif
 
 endef