Adding Qt5 base

Crosscompile and package Qt5 (base) and setup an
environment to easily crosscompile and package
other qmake based projects.

Please see the comments within the Makefiles
(Makefile / qmake.mk) for current limitations and
known issues.

Packaged from the "base" submodule herewith are:

 - qt5base-concurrent
 - qt5base-core
 - qt5base-gui
 - qt5base-network
 - qt5base-printSupport
 - qt5base-sql
 - qt5base-test
 - qt5base-widgets
 - qt5base-xml
 - qt5base-plugin-bearer-generic
 - qt5base-plugin-input-evdevkeyboard
 - qt5base-plugin-input-evdevmouse
 - qt5base-plugin-input-evdevtablet
 - qt5base-plugin-input-evdevtouch
 - qt5base-plugin-imageformats-gif
 - qt5base-plugin-imageformats-ico
 - qt5base-plugin-imageformats-jpeg
 - qt5base-plugin-platforms-linuxfb
 - qt5base-plugin-platforms-minimal
 - qt5base-plugin-platforms-offscreen
 - qt5base-plugin-sqldrivers-sqlite
 - qt5base-examples

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