[Qt] Use ICU if available

[Qt] Use ICU if available
https://bugs.webkit.org/show_bug.cgi?id=76821

Patch by Jesus Sanchez-Palencia <jesus.palencia@openbossa.org> on 2012-01-26
Reviewed by Simon Hausmann.

Source/WebCore:

Adding correct sources to a Qt 5 based build.

No new tests, it's just a build dependency change.

* Target.pri:

Source/WTF:

Adding libicu dependencies for a Qt5 based build.

* WTF.pri:

Tools:

Adding unicode defines for a Qt 5 based build.

* qmake/mkspecs/features/features.prf:

LayoutTests:

Unskipping ICU related tests for Qt 5 and skipping for
Qt 4.

* platform/qt-4.8/Skipped:
* platform/qt-arm/Skipped:
* platform/qt-wk2/Skipped:
* platform/qt/Skipped:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@105997 268f45cc-cd09-0410-ab3c-d52691b4dbfc