build: Fix test for SSE4.1 intrinsics

This change uses the `_mm_blend_epi16` SSE4.1 function used in our code
and fixes false-positive cases, for example, when CXXFLAGS="-mno-sse4.1"
provided.

Author: hebasto

configure.ac

@@ -504,11 +504,12 @@ TEMP_CXXFLAGS="$CXXFLAGS"
 CXXFLAGS="$SSE41_CXXFLAGS $CXXFLAGS"
 AC_MSG_CHECKING([for SSE4.1 intrinsics])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
-    #include <stdint.h>
     #include <immintrin.h>
   ]],[[
-    __m128i l = _mm_set1_epi32(0);
-    return _mm_extract_epi32(l, 3);
+    __m128i a = _mm_set1_epi32(0);
+    __m128i b = _mm_set1_epi32(1);
+    __m128i r = _mm_blend_epi16(a, b, 0xFF);
+    return _mm_extract_epi32(r, 3);
   ]])],
  [ AC_MSG_RESULT([yes]); enable_sse41=yes; AC_DEFINE([ENABLE_SSE41], [1], [Define this symbol to build code that uses SSE4.1 intrinsics]) ],
  [ AC_MSG_RESULT([no])]