ggml-cpu/x86: fix unused changemask warning in repack (ggml-org#20692)

Author: mrshaw01

ggml/src/ggml-cpu/arch/x86/repack.cpp

@@ -531,7 +531,6 @@ static void gemv_q4_b32_8x8_q8_0_lut_avx(int n, float * GGML_RESTRICT s, size_t
 
     UNUSED(bs);
 
-    __m128i changemask = _mm_set_epi8(15, 14, 7, 6, 13, 12, 5, 4, 11, 10, 3, 2, 9, 8, 1, 0);
     __m256i finalpermutemask = _mm256_set_epi32(7, 5, 3, 1, 6, 4, 2, 0);
 
     // Permute mask used for easier vector processing at later stages
@@ -580,6 +579,7 @@ static void gemv_q4_b32_8x8_q8_0_lut_avx(int n, float * GGML_RESTRICT s, size_t
                 if constexpr (
                         std::is_same_v<block_tx8, block_q4_0x8> ||
                         std::is_same_v<block_tx8, block_iq4_nlx8>) {
+                    const __m128i changemask = _mm_set_epi8(15, 14, 7, 6, 13, 12, 5, 4, 11, 10, 3, 2, 9, 8, 1, 0);
                     col_scale_f32 = GGML_F32Cx8_REARRANGE_LOAD(b_ptr[b].d, changemask);
                 } else if constexpr (std::is_same_v<block_tx8, block_mxfp4x8>) {
                     // Load 8 E8M0 exponents and convert to float via LUT