The default "simple runner" creates a log file whose name
is the append of the suite-name (from the initial test-begin) and ".log".
But the 'suite-name' is a string that can contain characters not suitable
for a filename.  This patch "sanitizes" the filename, converting questionable
characters to #\_.
--
	--Per Bothner
xxxxxx@bothner.com   http://per.bothner.com/