Bug 572338 - use only one file access instead of 4 to collect file
information

Change-Id: I14df62244b0cbcfc782e4bb17e0b25d4e3468d24
Signed-off-by: Carsten Hammer <carsten.hammer@t-online.de>
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.resources/+/175921
Tested-by: Platform Bot <platform-bot@eclipse.org>
Reviewed-by: Karsten Thoms <karsten.thoms@karakun.com>
Reviewed-by: Lars Vogel <Lars.Vogel@vogella.com>