Re-add qtjsbackend dependency for qtdeclarative in Qt 5.1.1

The dependency was removed in efd3f947a08e0976e24bc266de4ec229298115cf.
Since the .inc files are shared between the 5.1.1 and git recipes,
add the dependency in the 5.1.1 recipe.

Signed-off-by: Jacob Kroon <jacob.kroon@mikrodidakt.se>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>