Add stub for avx.
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2087343002
CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot

Review-Url: https://codereview.chromium.org/2087343002
diff --git a/gyp/opts.gypi b/gyp/opts.gypi
index fbc3d49..6db9d0c 100644
--- a/gyp/opts.gypi
+++ b/gyp/opts.gypi
@@ -49,13 +49,13 @@
         'sse41_sources': [
             '<(skia_src_path)/opts/SkOpts_sse41.cpp',
         ],
+        'avx_sources': [
+            '<(skia_src_path)/opts/SkOpts_avx.cpp',
+        ],
         # These targets are empty, but XCode doesn't like that, so add an empty file to each.
         'sse42_sources': [
             '<(skia_src_path)/core/SkForceCPlusPlusLinking.cpp',
         ],
-        'avx_sources': [
-            '<(skia_src_path)/core/SkForceCPlusPlusLinking.cpp',
-        ],
         'avx2_sources': [
             '<(skia_src_path)/core/SkForceCPlusPlusLinking.cpp',
         ],