Port HalfFloatRow_SSE2 to AVX2 but not using F16C.

include/libyuv/row.h

Index: include/libyuv/row.h
diff --git a/include/libyuv/row.h b/include/libyuv/row.h
index 09b24f91e99362a56fbb0d2a0160da3ece3de59b..df11bca1632023972d80343a97a8608b4892e2a3 100644
--- a/include/libyuv/row.h
+++ b/include/libyuv/row.h
@@ -201,6 +201,7 @@ extern "C" {
 #define HAS_COPYROW_AVX
 #define HAS_H422TOARGBROW_AVX2
 #define HAS_HALFFLOATROW_AVX2
+// #define HAS_HALFFLOATROW_F16C  // Enable to test halffloat cast
 #define HAS_I400TOARGBROW_AVX2
 #define HAS_I422TOARGB1555ROW_AVX2
 #define HAS_I422TOARGB4444ROW_AVX2
@@ -1931,11 +1932,14 @@ void ARGBPolynomialRow_AVX2(const uint8* src_argb,
 
 // Scale and convert to half float.
 void HalfFloatRow_C(const uint16* src, uint16* dst, float scale, int width);
+void HalfFloatRow_SSE2(const uint16* src, uint16* dst, float scale, int width);
+void HalfFloatRow_Any_SSE2(const uint16* src, uint16* dst, float scale,
+                           int width);
 void HalfFloatRow_AVX2(const uint16* src, uint16* dst, float scale, int width);
 void HalfFloatRow_Any_AVX2(const uint16* src, uint16* dst, float scale,
                            int width);
-void HalfFloatRow_SSE2(const uint16* src, uint16* dst, float scale, int width);
-void HalfFloatRow_Any_SSE2(const uint16* src, uint16* dst, float scale,
+void HalfFloatRow_F16C(const uint16* src, uint16* dst, float scale, int width);
+void HalfFloatRow_Any_F16C(const uint16* src, uint16* dst, float scale,
                            int width);
 
 void ARGBLumaColorTableRow_C(const uint8* src_argb, uint8* dst_argb, int width,