rng-tools: Update to version 2.16

rng-tools: Update to version 2.16

- This v2 version corrects an error where a debug echo statement was left in the lfs file
- Update from version 2.14 to 2.16
- Update of rootfile not required
- Version 2.16 required libcap to be available, which it is, but it could not be found by
   rng-tools. This is because rng-tools is using pkg-config and the required libcap.pc file
   was not stored in the standard directory location for .pc files. Therefore a patch for
   libcap is bundled together with this update to fix this.

Tested-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>