make Makefiles not depend on .qmake.super

sync with qmake. this is a no-op in qtc.

Change-Id: Id5158d7e272fdee4f4a041fb7c828295a0a86684
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
(cherry picked from qtbase/d135a311a34e693d761a3607663b0879be9bbf65)
find features/ under mkspecs/ of source & build root

we were finding features/ directly in the source & build root, and we
were finding features/ under mkspecs/ from $QMAKEPATH and other mkspecs
locations, but we omitted the "transitive hull". this was
counterintuitive.

Change-Id: I9823e6606467c98f264c81385250da92311f51ca
(cherry picked from qtbase/0bf65180b8710e4516496d0bc53a265ff0dd6a01)
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
make .qmake.{super,cache,conf} find "anchored" features

these files function as "anchors" for mkspecs/ and features/ directories
used by projects which load these files. ironically, these files didn't
see these feature files themselves.

Change-Id: I590855eb4a9d2c72b9abfcaa431d2f85a719c6e2
(cherry picked from qtbase/7456dfb4552c4e4f900af9fa8923828a23737280)
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
remove pointless string conversion

Change-Id: I1640083007ed0c428dfb8ab5ce8b68a7d7e2a749
(cherry picked from qtbase/d1b1b31c9237e0bd11c61fc54ad45551b7d862da)
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
introduce /src qmake property variants

this is for shadow builds during build time, where the respective files
are expected in the source dir.

Change-Id: I18dcfbdef99e1562a51dacac333642cae8105ebd
(cherry picked from qtbase/4531c83376c1a3546305a9fa5203e0a885e8860d)
Reviewed-by: Mitch Curtis <mitch.curtis@digia.com>
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
CppTools: Allow to force a "Parsing" notification

Task-number: QTCREATORBUG-9597

Change-Id: I726a818c7d4af35dcb4863f74b08cd639a189bdd
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
Project managers: Force "Parsing" notification

...so parsing progress will also be reported for projects consisting of
only one source file.

Task-number: QTCREATORBUG-9597

Change-Id: If35a00b6f949258d64921f144919269fa0c81d36
Reviewed-by: Daniel Teske <daniel.teske@digia.com>