fix minor portability issue, use printf

Rules.mak

@@ -463,7 +463,7 @@ ifeq ($(TARGET_ARCH),powerpc)
 # faster code.
 	PICFLAG:=-fpic
 	PIEFLAG_NAME:=-fpie
-	PPC_HAS_REL16:=$(shell echo -e "\t.text\n\taddis 11,30,_GLOBAL_OFFSET_TABLE_-.@ha" | $(CC) -c -x assembler -o /dev/null -  2> /dev/null && echo -n y || echo -n n)
+	PPC_HAS_REL16:=$(shell printf "\t.text\n\taddis 11,30,_GLOBAL_OFFSET_TABLE_-.@ha\n" | $(CC) -c -x assembler -o /dev/null -  2> /dev/null && echo -n y || echo -n n)
 	CPU_CFLAGS-$(PPC_HAS_REL16)+= -DHAVE_ASM_PPC_REL16
 	CPU_CFLAGS-$(CONFIG_E500) += "-D__NO_MATH_INLINES"