make stubs for dangerous/useless qmake functions in limited mode

sync up implementation with lupdate & creator. no actual effect on
qmake.

Change-Id: I1bdeb759e895e4200f09332dadf8a6cef348182f
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
(cherry picked from qttools/94ab2efb2d155d3c1ca7b91c1daf443a149bcf1f)
fetch all properties from qmake

sync up implementation with lupdate & creator. no actual effect on
qmake.

don't filter out ^QMAKE_.*:
- QMAKE_MKSPECS is not printed any more, so needs no filtering
- QMAKE_VERSION can be simply used now, as we are now rather close to the
  real qmake
- QMAKE_SPEC and QMAKE_XSPEC need to be fetched
  - this fixes the default spec resolution

Change-Id: Ifcfa8b5b9e2bbf5d995940e1bb7f55e7d67aed3e
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
(cherry picked from qttools/0037bef09ca77c5ae4d20bd09294ba1d57537e09)
add missing ifdefery

sync up implementation with qtcreator.

Change-Id: I6a1578818512fa3b0773faf276a1d56881eb06d7
(cherry picked from qttools/582cbddc6ba1b74a7e4e07e0b5c23d47de6838cb)
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
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
Reviewed-by: Joerg Bornemann <joerg.bornemann@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
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
remove pointless string conversion

Change-Id: I1640083007ed0c428dfb8ab5ce8b68a7d7e2a749
Reviewed-by: Joerg Bornemann <joerg.bornemann@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
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
don't copy mkspecs to build directory

instead, teach qmake to use the mkspecs dir from the source dir as well.

Change-Id: I9edac11f8997fcb0594d0a67419d4733dd4ed86b
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
don't copy/symlink doc/global to build dir

instead, use the files directly from the source dir.

Change-Id: I03b728c66de6e03cade6dc153dcc78cea8e3f606
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
Reviewed-by: Martin Smith <martin.smith@digia.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>