Use Debian/ububtu patchset

dev-qt/qtwebkit/files/reduce_exports.diff

@@ -0,0 +1,26 @@
+Description: reduce the number of exported symbols in libQt5WebKit.so.5
+Author: Dmitry Shachnev <mitya57@debian.org>
+Forwarded: not-needed
+Last-Update: 2017-08-27
+
+--- a/Source/WTF/wtf/ExportMacros.h
++++ b/Source/WTF/wtf/ExportMacros.h
+@@ -56,7 +56,7 @@
+ 
+ #elif defined(__GNUC__) && !defined(__CC_ARM) && !defined(__ARMCC__)
+ 
+-#define WTF_EXPORT_DECLARATION __attribute__((visibility("default")))
++#define WTF_EXPORT_DECLARATION
+ #define WTF_IMPORT_DECLARATION WTF_EXPORT_DECLARATION
+ #define WTF_HIDDEN_DECLARATION __attribute__((visibility("hidden")))
+ 
+--- a/Source/cmake/OptionsQt.cmake
++++ b/Source/cmake/OptionsQt.cmake
+@@ -706,6 +706,7 @@ if (COMPILER_IS_GCC_OR_CLANG AND UNIX)
+     if (NOT SHARED_CORE)
+         set(CMAKE_C_FLAGS "-fvisibility=hidden ${CMAKE_C_FLAGS}")
+         set(CMAKE_CXX_FLAGS "-fvisibility=hidden -fvisibility-inlines-hidden ${CMAKE_CXX_FLAGS}")
++        add_definitions(-DJS_NO_EXPORT)
+     endif ()
+ endif ()
+