configure.ac: print useful build config info
configure.ac: print useful build config info

Inspired by the GNOME Shell configure.ac

thisMagpie/java-atk-wrapper,GNOME/java-atk-wrapper,GNOME/java-atk-wrapper,GNOME/java-atk-wrapper,thisMagpie/java-atk-wrapper,thisMagpie/java-atk-wrapper