Merge pull request micropython#8633 from jepler/fix-frozen-modules-build

Fix build error when frozen modules are updated

Author: dhalbert

py/circuitpy_defns.mk

@@ -877,4 +877,4 @@ invalid-board:
 # Print out the value of a make variable.
 # https://stackoverflow.com/questions/16467718/how-to-print-out-a-variable-in-makefile
 print-%:
-	@echo $* = $($*)
+	@echo "$* = "$($*)