Only add stubdata.c once on Windows (when icu_use_data_file_flag is set)

It defaults to 1 everywhere except android webview, but it looks like
the windows condition wasn't updated after the switch.

TBR=jshin@chromium.org
R=jam@chromium.org
BUG=404809

Review URL: https://codereview.chromium.org/486103002

git-svn-id: http://src.chromium.org/svn/trunk/deps/third_party/icu52@291179 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
diff --git a/icu.gyp b/icu.gyp
index aaec2f8..770bf9c 100644
--- a/icu.gyp
+++ b/icu.gyp
@@ -326,7 +326,7 @@
             [ 'use_system_icu==0 and want_separate_host_toolset==0', {
               'toolsets': ['target'],
             }],
-            [ 'OS == "win"', {
+            [ 'OS == "win" and icu_use_data_file_flag==0', {
               'sources': [
                 'source/stubdata/stubdata.c',
               ],