exec_tools: don't bork daemons when no verbosity level

This is an emergency fix, that lets "cf-serverd" run again!


At commit 4ddf558fc88047ad a loop was introduced, that scanned the
report context to find file descriptors we shouldn't close.

But, when no "-I", "-v", or "-d" options are given, the daemon would
have report_context == NULL !

So, we'd better skip the whole loop and use the shorter loop, like
before that commit.

Note that this bug had prevented cf-serverd from running at all!