qt_functions: temporary remove isEmpty check

* now we assume that every build will provide QT_EXTERNAL_HOST_BINS value

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
configure: Add ExternalHostBinaries and Sysroot to bin/qt.conf

* ExternalHostBinaries isn't set in qtbase-native, so we need to force it for target qtbase
* Sysroot value is different between qtbase-native and qtbase, this is different then when
  qtbase is built host_build + device_build together
configureapp: Prefix default LIBDIRS and INCDIRS with SYSROOT

Change-Id: I275b30f67bc477d8e9a008f4894198859ec45017
qt_module: Fix pkgconfig replacement

* in situation like this:
  QT_SYSROOT:/OE/oe-core/tmp-eglibc/sysroots/qemuarm
  QT_INSTALL_LIBS:/OE/oe-core/tmp-eglibc/sysroots/qemuarm/usr/lib
  QT_INSTALL_LIBS/raw:/usr/lib
  QT_INSTALL_LIBS/get:/OE/oe-core/tmp-eglibc/work/armv5te-oe-linux-gnueabi/qtbase/5.0.0-r0.0/build/lib

  I don't want the replacement like this:
  sed
    -e "s,/OE/oe-core/tmp-eglibc/work/armv5te-oe-linux-gnueabi/qtbase/5.0.0-r0.0/build/include,/usr/include/qt5,g"
    -e "s,/OE/oe-core/tmp-eglibc/work/armv5te-oe-linux-gnueabi/qtbase/5.0.0-r0.0/build/lib,/usr/lib,g"
    "../../lib/pkgconfig/Qt5Core.pc"
    >"/OE/oe-core/tmp-eglibc/work/armv5te-oe-linux-gnueabi/qtbase/5.0.0-r0.0/image/OE/oe-core/tmp-eglibc/sysroots/qemuarm/usr/lib/pkgconfig/Qt5Core.pc"
  because that way I'll end with -L/usr/lib in .pc file which is
  cross-compile unfriendly, keeping ${libdir}/${includedir} works better
  in my case

Change-Id: Id0f9143c012b7fe7bb7bab0055687f4e0517f653
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
qmake/property: rename QT_INSTALL_CONFIGURATION to QT_INSTALL_SETTINGS

* this variable is referenced from configure and configureapp.cpp as QT_INSTALL_SETTINGS
  property.cpp was only place using name QT_INSTALL_CONFIGURATION

Upstream-Status: Submitted
https://codereview.qt-project.org/54912

Change-Id: I3ba40d5f8773fe9aea728c5b2418aa55cecc92da
qt_module: Fix paths in .prl files

* qmake does not prefix them with QT_SYSROOT when using them
  so e.g. when building qtdeclarative we get -L/usr/lib to LINKAGE
  variable, which is unsafe for cross-compilation
* writting QT_SYSROOT in .prl files is dangerous for sstate when
  builds are in different directories, so we need
  SSTATE_SCAN_FILES += "*.pri *.prl"
  to make them relocateble

Change-Id: I4b66dcad539a3ba876d8e4ee2eb2ccd626cd03ea
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>