If RESOURCES contained a non-existent .qrc file, qmake produced
Makefiles that resulted in an infinite loop when running GNU Make.
Introduce a new extra compiler CONFIG value "remove_no_exist" that
removes non-existent extra compiler input. This value is now used in the
extra compiler that handles the RESOURCES variable.
The difference to the existing CONFIG value "ignore_no_exist" is that
qmake still prints a warning about the non-existent file.
Pick-to: 6.5
Fixes: QTBUG-112743
Change-Id: I3293af75b75f217e1a1738b49da0af1117cfdecb
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>