Fix Make 3.8 compatibility issues in examples Makefile

examples/Makefile

@@ -1,16 +1,14 @@
 EXAMPLES = audioplayer cpptest ctest dfsdemo eepromfstest mixertest mptest mputest rspqdemo spritemap test timers vrutest vtest ucodetest
 
-# Populated by evaluating the EXAMPLE_template macro for each example
-all:
-clean:
+all: $(EXAMPLES)
+clean: $(foreach example,$(EXAMPLES),$(example)-clean)
+.PHONY: all clean
 
-define EXAMPLE_template =
+define EXAMPLE_template
 $(1):
 	$$(MAKE) -C $(1)
 $(1)-clean:
 	$$(MAKE) -C $(1) clean
-all: $(1)
-clean: $(1)-clean
 .PHONY: $(1) $(1)-clean
 endef