Add a runtime data dependency on icudtl.dat in the GN build.

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 351fbb10a0bb413e241e1344b4fef46538927d83..5b8c0b1470552e0f3e9133e1a707680665a3e491 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -517,6 +517,10 @@ if (icu_use_data_file) {
       outputs = [
         "$root_out_dir/icudtl.dat",
       ]
+
+      data = [
+        "$root_out_dir/icudtl.dat",
+      ]
     }
   }
 } else {
@@ -529,6 +533,10 @@ if (icu_use_data_file) {
       outputs = [
         "$root_out_dir/icudt.dll",
       ]
+
+      data = [
+        "$root_out_dir/icudtl.dll",
+      ]
     }
   } else {
     source_set("icudata") {