Add Doxygen description for qbipc_common.h
Add Doxygen description for qbipc_common.h

The generated manpage lacked the whatis/apropos text in the synopsis.

gao-yan/libqb,rubenk/libqb,gao-yan/libqb,ClusterLabs/libqb,rubenk/libqb,ClusterLabs/libqb,kgaillot/libqb,kgaillot/libqb,ClusterLabs/libqb,kgaillot/libqb