Host tools may be built using target dbus flags

There is only a single variable QT_CFLAGS_DBUS (the same for QT_LIBS_DBUS) that is set using

QT_CFLAGS_DBUS=`$PKG_CONFIG --cflags dbus-1 2>/dev/null`

However PKG_CONFIG returns the information for the target device. This variable is then used for both host and target tools.

We currently hack around this after configure:

sed -i '/^QT_CFLAGS_DBUS/{i\
host_build: QT_CFLAGS_DBUS = '"$HOST_DBUS_CFLAGS"'
s/^/else: /};/^QT_LIBS_DBUS/{i\
host_build: QT_LIBS_DBUS = '"$HOST_DBUS_LIBS"'
s/^/else: /}' ./qtbase/mkspecs/qmodule.pri