Add scalar version of hwc2spchw convolution.

PiperOrigin-RevId: 276274887
diff --git a/BUILD b/BUILD
index 573db85..590f0da 100644
--- a/BUILD
+++ b/BUILD
@@ -78,6 +78,7 @@
     "src/f32-avgpool/mp9p8q-scalar.c",
     "src/f32-avgpool/up9-scalar.c",
     "src/f32-clamp/scalar.c",
+    "src/f32-conv-hwc2spchw/3x3s2p1c3x4-scalar-1x1.c",
     "src/f32-igemm/1x4-scalar.c",
     "src/f32-igemm/2x4-scalar.c",
     "src/f32-igemm/4x2-scalar.c",
@@ -895,6 +896,17 @@
 )
 
 xnnpack_benchmark(
+    name = "f32_conv_hwc2spchw_bench",
+    srcs = [
+        "bench/f32-conv-hwc2spchw.cc",
+        "bench/dconv.h",
+        "src/xnnpack/AlignedAllocator.h",
+    ] + WEIGHTS_PACK_HDRS + MICROKERNEL_BENCHMARK_HDRS,
+    copts = ["-Wno-unused-function"],
+    deps = MICROKERNEL_BENCHMARK_DEPS,
+)
+
+xnnpack_benchmark(
     name = "f32_dwconv_bench",
     srcs = [
         "bench/f32-dwconv.cc",