simd_impl.h,SIMD_TUPLE: make name param type explicit

fixes an error under Xcode 8:
array initializer must be an initializer list or string literal
the type deduced from #name was e.g., char[11]

Change-Id: I6fcb29e3229db7650eee106ef6e3986515dc0a07

test/simd_impl.h

diff --git a/test/simd_impl.h b/test/simd_impl.h
index ce41fb6..c0b7fd0 100644
--- a/test/simd_impl.h
+++ b/test/simd_impl.h
@@ -195,7 +195,7 @@
   INSTANTIATE_TEST_CASE_P(name, type, ::testing::Values(__VA_ARGS__))
 
 #define SIMD_TUPLE(name, mask, maskwidth) \
-  std::tr1::make_tuple(mask, maskwidth, #name)
+  std::tr1::make_tuple(mask, maskwidth, static_cast<const char *>(#name))
 
 INSTANTIATE(ARCH, ARCH_POSTFIX(U32_V64V64),
             (SIMD_TUPLE(v64_sad_u8, 0U, 0U), SIMD_TUPLE(v64_ssd_u8, 0U, 0U)));