Fix issue 1382: chown .sconsign.dblite back to original user/group when done, when running as root.  If it didn't exist, chown to user who executed sudo if known.  Hard to test automatically because test needs to run as root.
Fix issue 1382: chown .sconsign.dblite back to original user/group when done, when running as root.  If it didn't exist, chown to user who executed sudo if known.  Hard to test automatically because test needs to run as root.

git-svn-id: 7892167f69f80ee5d3024affce49f20c74bcb41d@4189 fdb21ef1-2011-0410-befe-b5e4ea1792b1

azverkan/scons,azverkan/scons,azverkan/scons,azverkan/scons,azverkan/scons