[Nix] Cleanup Source/WebCore/PlatformNix.cmake
https://bugs.webkit.org/show_bug.cgi?id=126226

Reviewed by Csaba Osztrogonác.

No new tests needed.

* PlatformNix.cmake:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@161094 268f45cc-cd09-0410-ab3c-d52691b4dbfc
Small build fix for the GTK+ CMake port

Source/WebKit/gtk:

* tests/CMakeLists.txt: Output the WebKit1 GObject API unit tests to the proper directory
and fix the path to the generated API source.

Source/WebKit2:

* UIProcess/API/gtk/tests/CMakeLists.txt: Make the way the output directory is specified similar
to the WebKit1 version of these tests, so that it is more difficult to inadvertently specify the
wrong directory.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@161095 268f45cc-cd09-0410-ab3c-d52691b4dbfc