lib/raid6: check for assembler SSSE3 support

Allow the x86 SSSE3 recovery function to be tested in raid6test.

Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
Signed-off-by: Shaohua Li <shli@fb.com>

lib/raid6/test/Makefile

@@ -34,6 +34,9 @@ endif
 
 ifeq ($(IS_X86),yes)
         OBJS   += mmx.o sse1.o sse2.o avx2.o recov_ssse3.o recov_avx2.o avx512.o recov_avx512.o
+        CFLAGS += $(shell echo "pshufb %xmm0, %xmm0" |		\
+                    gcc -c -x assembler - >&/dev/null &&	\
+                    rm ./-.o && echo -DCONFIG_AS_SSSE3=1)
         CFLAGS += $(shell echo "vpbroadcastb %xmm0, %ymm1" |	\
                     gcc -c -x assembler - >&/dev/null &&	\
                     rm ./-.o && echo -DCONFIG_AS_AVX2=1)