Add RLZ build file for GN build, fix Windows build.

tools/gn/secondary/third_party/icu/BUILD.gn

Index: tools/gn/secondary/third_party/icu/BUILD.gn
diff --git a/tools/gn/secondary/third_party/icu/BUILD.gn b/tools/gn/secondary/third_party/icu/BUILD.gn
index e4d030a8d3781acbfb74037b616fc6f6bc6576ff..df268cb145c9f97b9c3115bfac2a88eb44649216 100644
--- a/tools/gn/secondary/third_party/icu/BUILD.gn
+++ b/tools/gn/secondary/third_party/icu/BUILD.gn
@@ -16,6 +16,11 @@ config("icu_config") {
   defines = [
     "U_USING_ICU_NAMESPACE=0",
   ]
+
+  if (component_mode != "shared_library") {
+    defines += [ "U_STATIC_IMPLEMENTATION" ]
+  }
+
   include_dirs = [
     "source/common",
     "source/i18n",
@@ -24,10 +29,6 @@ config("icu_config") {
 
 # Config used only by ICU code.
 config("icu_code") {
-  if (component_mode != "shared_library") {
-    defines = [ "U_STATIC_IMPLEMENTATION" ]
-  }
-
   if (is_win) {
     # Disable some compiler warnings.
     cflags = [