LU-3549 llapi: add printf attribute to llapi_{printf,error}

LU-3549 llapi: add printf attribute to llapi_{printf,error}

Add printf attributes to llapi_printf and llapi_error for compile time
checking that the format string agrees with the argument list, and
const qualify the format parameter of both functions. Fixup the
mismatched calls to these functions.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Signed-off-by: JC Lafoucriere <jacques-charles.lafoucriere@cea.fr>
Change-Id: Ic8df148abb0bfe8ce72d05d76cb7ce0f1832c28f
Reviewed-on: http://review.whamcloud.com/6867
Tested-by: Hudson
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>