Fix wrong header file name in QMLJS

Fix a qmake warning introduced in e1b44e870f5c15 .

Change-Id: I8f7913ceabc411044785634d1708fbc035b0a5c4
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>