Goals from top level Makefile should be known even if empty.

src/Makefile

@@ -1,3 +1,7 @@
+.SUFFIXES:
+
+.PHONY: all bin $(PROGS) mostlyclean clean install avail unavail
+
 ifeq ($(shell echo),)
 
 PROGS = ar65  \
@@ -30,10 +34,6 @@ LDLIBS += -lm
 
 INSTALL = install
 
-.SUFFIXES:
-
-.PHONY: all bin $(PROGS) mostlyclean clean install avail unavail
-
 all bin: $(PROGS)
 
 mostlyclean:
@@ -116,10 +116,6 @@ $(foreach prog,$(PROGS),$(eval $(call PROG_template,$(prog))))
 
 else # cmd.exe
 
-.SUFFIXES:
-
-.PHONY: all bin mostlyclean clean
-
 all bin:
 	msbuild cc65.sln /p:configuration=release /consoleloggerparameters:disableconsolecolor
 
@@ -129,4 +125,6 @@ mostlyclean:
 clean:
 	msbuild cc65.sln /p:configuration=release /consoleloggerparameters:disableconsolecolor /target:$@
 
+install avail unavail:
+
 endif # cmd.exe