Oswald Buddenhagen authored Aug 23, 2016 and Oswald Buddenhagen committed Oct 25, 2016

this function discards all values that come from a specific file. it
will be needed for configure bootstrapping, but is too obscure to
document it for general use.

Change-Id: I62c18aeb1847712e33d0599dbb0b90ffa1722438
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
(cherry picked from qtbase/12bb328bb0be8efe54aae750c21938aab4d17539)