Windows/Windows CE: Do not dynamically load shell32/coredll.

Those libraries are contained in QMAKE_LIBS_CORE and
GetSpecialFolderPath() is present in all supported versions.

Change-Id: Iae40714e0f234625b063aeb50e29fc79c4aaa6ea
Reviewed-by: Björn Breitmeyer <bjoern.breitmeyer@kdab.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>