Update unrar to v5.1.6.

5.1.6.tar.gz - 5.10.0 in the rc file.
Remove duplicate semicolons.
TreePropSheet/PropPageFrameDefault.cpp: remove custom code for pre XP.
coverity.bat build both arches and clean outside of the coverity tool.
Fix uninitialized scalar fields.
Remove dead conditional.

The whole code is in a `while (nDelta != 0)`.