[MPLAY32]: Improve ShowLastWin32Error().

git-svn-id: svn://svn.reactos.org/reactos/trunk/reactos@63960 97493ccd-5924-5043-b1f5-66cb403b36ce
[TASKMGR]
- Simplify EnablePrivilege().
- Add "Lock computer" option to the shutdown menu.
- Display the last error description if something failed when selecting one of the shutdown options.
Inspired by the patch of Robert Naumann (see CORE-8048).
CORE-8048 #resolve #comment I adapted some of your ideas to what I already committed in revision 63955, thanks!

git-svn-id: svn://svn.reactos.org/reactos/trunk/reactos@63961 97493ccd-5924-5043-b1f5-66cb403b36ce
[PSDK]
Add two missing constants


git-svn-id: svn://svn.reactos.org/reactos/trunk/reactos@63962 97493ccd-5924-5043-b1f5-66cb403b36ce
[EVENTLOG]
Fix crash in LogfCreate when LogName is NULL.
strsafe.h++;


git-svn-id: svn://svn.reactos.org/reactos/trunk/reactos@63965 97493ccd-5924-5043-b1f5-66cb403b36ce
strsafe.h++;


git-svn-id: svn://svn.reactos.org/reactos/trunk/reactos@63966 97493ccd-5924-5043-b1f5-66cb403b36ce
[TASKMGR]
German translation update. / Fix the "&" locations to follow the Windows XP GER way.

git-svn-id: svn://svn.reactos.org/reactos/trunk/reactos@63967 97493ccd-5924-5043-b1f5-66cb403b36ce