port scaledownby4_avx2 to gcc

include/libyuv/scale_row.h

 /*
  *  Copyright 2013 The LibYuv Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS. All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 52 matching lines @@
 #define HAS_SCALEADDROW_SSE2
 #endif
 
 // The following are available on all x86 platforms, but
 // require VS2012, clang 3.4 or gcc 4.7.
 // The code supports NaCL but requires a new compiler and validator.
 #if !defined(LIBYUV_DISABLE_X86) && (defined(VISUALC_HAS_AVX2) || \
     defined(CLANG_HAS_AVX2) || defined(GCC_HAS_AVX2))
 #define HAS_SCALEADDROW_AVX2
 #define HAS_SCALEROWDOWN2_AVX2
-#endif
-
-// The following are available for Visual C and clangcl 32 bit:
-#if !defined(LIBYUV_DISABLE_X86) && defined(_M_IX86) && \
-    (defined(VISUALC_HAS_AVX2) || defined(CLANG_HAS_AVX2))
 #define HAS_SCALEROWDOWN4_AVX2
 #endif
 
 // The following are available on Neon platforms:
 #if !defined(LIBYUV_DISABLE_NEON) && !defined(__native_client__) && \
     (defined(__ARM_NEON__) || defined(LIBYUV_NEON) || defined(__aarch64__))
 #define HAS_SCALEARGBCOLS_NEON
 #define HAS_SCALEARGBROWDOWN2_NEON
 #define HAS_SCALEARGBROWDOWNEVEN_NEON
 #define HAS_SCALEFILTERCOLS_NEON
@@ skipping 399 matching lines @@
 void ScaleRowDown38_3_Box_MIPS_DSPR2(const uint8* src_ptr,
                                      ptrdiff_t src_stride,
                                      uint8* dst_ptr, int dst_width);
 
 #ifdef __cplusplus
 }  // extern "C"
 }  // namespace libyuv
 #endif
 
 #endif  // INCLUDE_LIBYUV_SCALE_ROW_H_  NOLINT