Unbust the old debugger

AFAICT the recent STL changes have introduced some QT conflicts.

GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1753813002

Review URL: https://codereview.chromium.org/1753813002
diff --git a/gyp/debugger.gyp b/gyp/debugger.gyp
index cac7d5a..d6b97a7 100644
--- a/gyp/debugger.gyp
+++ b/gyp/debugger.gyp
@@ -53,7 +53,7 @@
       [ 'skia_os == "win"', {
         'variables': {
           # This is the default location for the version of Qt current on 10/11/12
-          'qt_sdk%': 'C:/Qt/4.8.3/',
+          'qt_sdk%': 'C:/Qt/4.8.6/',
         },
         'qt_sdk': '<(qt_sdk)',
         'qt_moc%': '<(qt_sdk)/bin/moc',