QtWebEngine 5.9.3 fails to build against system ICU 60.1.

../../3rdparty/chromium/components/url_formatter/url_formatter.cc:511:2: error: #error "Update aspirational_scripts per Unicode 10.0"
 #error "Update aspirational_scripts per Unicode 10.0"
  ^~~~~

--- a/src/3rdparty/chromium/components/url_formatter/url_formatter.cc	2017-11-08 21:13:31.000000000 +0200
+++ b/src/3rdparty/chromium/components/url_formatter/url_formatter.cc	2017-11-30 16:37:00.116153976 +0200
@@ -488,7 +488,7 @@
   // are added to the allowed set. The list has to be updated when a new
   // version of Unicode is released. The current version is 9.0.0 and ICU 60
   // will have Unicode 10.0 data.
-#if U_ICU_VERSION_MAJOR_NUM < 60
+#if U_ICU_VERSION_MAJOR_NUM < 60 || defined(TOOLKIT_QT)
   const icu::UnicodeSet aspirational_scripts(
       icu::UnicodeString(
           // Unified Canadian Syllabics