Bug#27344 Total failure to start the server

- Give some more protection against "too long socket name by setting the max
length when to use a tmpdir for sockets to 70 

mysql-test/mysql-test-run.pl

@@ -1051,7 +1051,7 @@ sub command_line_setup () {
   # On some operating systems, there is a limit to the length of a
   # UNIX domain socket's path far below PATH_MAX, so try to avoid long
   # socket path names.
-  $sockdir = tempdir(CLEANUP => 0) if ( length($sockdir) >= 80 );
+  $sockdir = tempdir(CLEANUP => 0) if ( length($sockdir) >= 70 );
 
   # Put this into a hash, will be a C struct