make color emoji gm portable

tools/sk_tool_utils.cpp

Index: tools/sk_tool_utils.cpp
diff --git a/tools/sk_tool_utils.cpp b/tools/sk_tool_utils.cpp
index b06fcda3a6d8d360ee60d657cae32bc8021c6df0..08c7b4747d40f49a137428e8cc0b105df07898e0 100644
--- a/tools/sk_tool_utils.cpp
+++ b/tools/sk_tool_utils.cpp
@@ -20,6 +20,17 @@ DEFINE_bool(resourceFonts, false, "Use resource fonts");
 
 namespace sk_tool_utils {
 
+const char* platform_os_emoji() {
+    const char* osName = platform_os_name();
+    if (!strcmp(osName, "Android") || !strcmp(osName, "Unbuntu")) {
+        return "CBDT";
+    }
+    if (!strncmp(osName, "Mac", 3)) {
+        return "SBIX";
+    }
+    return "";
+}
+
 const char* platform_os_name() {
     for (int index = 0; index < FLAGS_key.count(); index += 2) {
         if (!strcmp("os", FLAGS_key[index])) {