spin off easy stuff from Herb's windows GN CL

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 3fae15135debdff18f9e1a3524d4b563c03eb05f..62d7470674dd1b85e11d93a648a19a6ffa967c6f 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -53,6 +53,7 @@ config("skia_private") {
     "src/ports",
     "src/sfnt",
     "src/utils",
+    "src/utils/win",
     "third_party/etc1",
     "third_party/ktx",
   ]
@@ -174,7 +175,9 @@ component("skia") {
     "//third_party/zlib",
   ]
 
-  libs = [ "pthread" ]
+  if (!is_win) {
+    libs = [ "pthread" ]
+  }
 
   sources = []
   sources += core_gypi.sources
@@ -245,6 +248,7 @@ component("skia") {
       "src/ports/SkTypeface_win_dw.cpp",
       "src/xps/SkDocument_XPS.cpp",
     ]
+    sources -= [ "src/utils/SkThreadUtils_pthread.cpp" ]
   } else {
     sources += [
       "src/ports/SkDebug_stdio.cpp",