Use Qt's RTTI setting when building ANGLE statically.

Prevent errors when building Qt statically with RTTI enabled:

warning C4743: 'const std::ios_base::failure::`vftable'' has different size in 'qtbase\src\3rdparty\angle\src\libGLESv2\Context.cpp' and '(...)': 16 and 12 bytes

Task-number: QTBUG-36951

Change-Id: Ie0501b986be8610c8293cd5c1aa42b502d7c27a1
Reviewed-by: Andrew Knight <andrew.knight@digia.com>
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>

src/angle/src/config.pri

@@ -54,7 +54,7 @@ angle_d3d11 {
 CONFIG(debug, debug|release) {
     DEFINES += _DEBUG
 } else {
-    CONFIG += rtti_off
+    !static: CONFIG += rtti_off
     DEFINES += NDEBUG
 }