switch skia to use skcms.gni

On the road to removing skcms/BUILD.gn,
and making configuring skcms a little less inside-out.

CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

Change-Id: I3c37c019bbc32a6112d329429f906b3d8b7f0d19
Reviewed-on: https://skia-review.googlesource.com/128304
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Mike Klein <mtklein@chromium.org>

BUILD.gn

@@ -775,12 +775,33 @@ optional("raw") {
   ]
 }
 
+import("third_party/skcms/skcms.gni")
+config("third_party_skcms_public") {
+  include_dirs = [ "third_party/skcms" ]
+}
+source_set("third_party_skcms") {
+  public_configs = [ ":third_party_skcms_public" ]
+
+  cflags = []
+  if (!is_win || is_clang) {
+    cflags += [
+      "-w",
+      "-std=c11",
+    ]
+  }
+
+  public = [
+    "third_party/skcms/skcms.h",
+  ]
+  sources = rebase_path(skcms_sources, ".", "third_party/skcms")
+}
+
 optional("skcms") {
   enabled = skia_use_skcms
 
   public_defines = [ "SK_USE_SKCMS" ]
   deps = [
-    "third_party/skcms",
+    ":third_party_skcms",
   ]
   sources = [
     "src/core/SkColorSpaceXform_skcms.cpp",
@@ -1421,9 +1442,9 @@ if (skia_enable_tools) {
       ":experimental_svg_model",
       ":flags",
       ":skia",
+      ":third_party_skcms",
       ":tool_utils",
       "//third_party/libpng",
-      "//third_party/skcms",
       "//third_party/zlib",
     ]
     public_deps = [