Stop build the log strings on the stack: we are multi-threaded now, and this is like...

Stop build the log strings on the stack: we are multi-threaded now, and this is like asking for problems. Instead, put them in the logging event. Note the use of partial initializer in _XBT_LOG_PRE: we only set the value of the first byte, the rest will be zeroed by the compiler

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/simgrid/simgrid/trunk@4148 48e7efb5-ca39-0410-a469-dd3cf9ba447f