kde-apps: Add WEBKIT_REQUIRED=always based on libQtWebKit.so.4 in NEEDED

kde-apps: Add WEBKIT_REQUIRED=always based on libQtWebKit.so.4 in NEEDED

kde-apps/kdepim-common-libs:
In file included from composereditor-ng/composerview.h:24:0, [...]
/usr/include/KDE/KWebView:1:25: fatal error: ../kwebview.h: No such file or directory

kde-apps/plasma-runtime:
graphicswidgetsbindingsplugin.dir/graphicswidgetsbindingsplugin.cpp.o:
undefined reference to `non-virtual thunk to Plasma::WebView::sizeHint(
	Qt::SizeHint, QSizeF const&) const'
collect2: error: ld returned 1 exit status
make[2]: *** [plasma/declarativeimports/graphicswidgets/CMakeFiles/
	graphicswidgetsbindingsplugin.dir/build.make:140:
	lib/libgraphicswidgetsbindingsplugin.so] Error 1

kde-apps/kdebase-kioslaves:
>>> package: kde-base/kdelibs-4.14.22
 *  - /usr/lib64/libkdewebkit.so.5
 *  - /usr/lib64/libkdewebkit.so.5.14.21
 *      used by /usr/lib64/kde4/htmlthumbnail.so

Package-Manager: portage-2.2.28