Move files in GN

Change-Id: I9873a1fb6e72cc0d567bb994b11c1af493ad3dd4
Reviewed-on: https://skia-review.googlesource.com/c/165901
Commit-Queue: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>

gn/core.gni

@@ -149,7 +149,6 @@ skia_core_sources = [
   "$_src/core/SkGpuBlurUtils.cpp",
   "$_src/core/SkGraphics.cpp",
   "$_src/core/SkHalf.cpp",
-  "$_src/core/SkHalf.h",
   "$_src/core/SkICC.cpp",
   "$_src/core/SkImageFilter.cpp",
   "$_src/core/SkImageFilterCache.cpp",
@@ -196,7 +195,6 @@ skia_core_sources = [
   "$_src/core/SkNormalMapSource.h",
   "$_src/core/SkNormalSource.cpp",
   "$_src/core/SkNormalSource.h",
-  "$_src/core/SkNx.h",
   "$_src/core/SkOpts.cpp",
   "$_src/core/SkOpts.h",
   "$_src/core/SkOrderedReadBuffer.h",
@@ -424,8 +422,6 @@ skia_core_sources = [
   "$_src/opts/SkBlitMask_opts.h",
   "$_src/opts/SkBlitRow_opts.h",
   "$_src/opts/SkChecksum_opts.h",
-  "$_src/opts/SkNx_neon.h",
-  "$_src/opts/SkNx_sse.h",
   "$_src/opts/SkRasterPipeline_opts.h",
   "$_src/opts/SkSwizzler_opts.h",
   "$_src/opts/SkUtils_opts.h",
@@ -439,10 +435,14 @@ skia_core_sources = [
   "$_include/private/SkFixed.h",
   "$_include/private/SkFloatBits.h",
   "$_include/private/SkFloatingPoint.h",
+  "$_include/private/SkHalf.h",
   "$_include/private/SkMalloc.h",
   "$_include/private/SkMessageBus.h",
   "$_include/private/SkMutex.h",
   "$_include/private/SkNoncopyable.h",
+  "$_include/private/SkNx.h",
+  "$_include/private/SkNx_neon.h",
+  "$_include/private/SkNx_sse.h",
   "$_include/private/SkOnce.h",
   "$_include/private/SkPathRef.h",
   "$_include/private/SkSemaphore.h",