Fix echo not interpreting newline in Makefile (#501)

Author: horstle

Makefile

@@ -80,10 +80,10 @@ build: clean
 
 multizip: clean
 	@-$(foreach abi,$(KODI_PYTHON_ABIS), \
-		echo "cd /addon/requires/import[@addon='xbmc.python']/@version\nset $(abi)\nsave\nbye" | xmllint --shell addon.xml; \
+		echo -e "cd /addon/requires/import[@addon='xbmc.python']/@version\nset $(abi)\nsave\nbye" | xmllint --shell addon.xml; \
 		matrix=$(findstring $(abi), $(word 1,$(KODI_PYTHON_ABIS))); \
 		if [ $$matrix ]; then version=$(version)+matrix.1; else version=$(version); fi; \
-		echo "cd /addon/@version\nset $$version\nsave\nbye" | xmllint --shell addon.xml; \
+		echo -e "cd /addon/@version\nset $$version\nsave\nbye" | xmllint --shell addon.xml; \
 		make zip; \
 	)