Migrate configuration lefovers to new configure system

Use new configure system for all package detection.
Move config test execution to new configure system.
However, keep old configure.prf for error hanlding.
Split configuration summary into:
 * optional system libraries used
 * required system libraries
 * required system libraries for qpa-xcb (on linux)

Change-Id: I5108456caa024a1ada9bb54750693064a2d36f78
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>