SmartCard::ReaderStatus: some fixes

• If GETEVENTCOUNTER fails, use -1 instead of 0 as the return value, such that the counter is seen to change when GETEVENTCOUNTER eventually succeeds. Should fix kolab/issue4191 (gpg4win Test B/5).
• Don't try 3 times to execute the same command. Hope that the event counter changes in those cases that we care about.

svn path=/branches/kdepim/enterprise4/kdepim/; revision=1100744