Fix a bug in the SipHash tests causing them to fail on Big Endian

There was nothing wrong with the SipHash implementation itself, just the
test. It accidently changed Grapheme32 array to little endian instead of
making Grapheme32_LE array little endian.

src/strings/siphash/test.c

@@ -61,9 +61,9 @@ int testmvm (void) {
 	size_t s_len = 9;
 	uint64_t t0, t1, t2, t3;
 	int32_t Grapheme32[9] = { 171, -72, 69, 76, 76, 79, 9829, 9826, 187  };
-	int32_t Grapheme32_LE[9] = { 171, -72, 69, 76, 76, 79, 9829, 9826, 187  };
+	int32_t Grapheme32_LE[9];
 	for (i = 0; i < 9; i++) {
-		Grapheme32[i] = MVM_TO_LITTLE_ENDIAN_32(Grapheme32[i]);
+		Grapheme32_LE[i] = MVM_TO_LITTLE_ENDIAN_32(Grapheme32[i]);
 	}
 	t0 = gettime_ns();
 	for (rep_count = 0; rep_count < REPEATS; rep_count++) {