raid6/test: replace echo -e with printf

-e is a non-standard echo option, echo output is
implementation-dependent when it is used. Replace echo -e with printf as
suggested by POSIX echo manual.

Cc: NeilBrown <neilb@suse.de>
Cc: Jim Kukunas <james.t.kukunas@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Acked-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NMax Filippov <jcmvbkbc@gmail.com>
Signed-off-by: NNeilBrown <neilb@suse.de>

lib/raid6/test/Makefile

@@ -28,7 +28,7 @@ ifeq ($(IS_X86),yes)
                     gcc -c -x assembler - >&/dev/null &&	\
                     rm ./-.o && echo -DCONFIG_AS_AVX2=1)
 else
-        HAS_ALTIVEC := $(shell echo -e '\#include <altivec.h>\nvector int a;' |\
+        HAS_ALTIVEC := $(shell printf '\#include <altivec.h>\nvector int a;\n' |\
                          gcc -c -x c - >&/dev/null && \
                          rm ./-.o && echo yes)
         ifeq ($(HAS_ALTIVEC),yes)