osutil: cleanups - use tabs - eliminate old-style function pointer calls - eliminate weird scoping - eliminate assignment-in-iff - use !foo rather than foo == NULL

Execution bit detection fixes for VFAT on Linux On Linux VFAT execution mode can be modified, but changes don't persist a filesy stem remount. The current test can be trickled by this. We can help with the det ection of VFAT checking whether new files get created with the execution bits on (as usually these partitions are mounted with the exec option, for convenience) .