some more coverity fixes

apt-pkg/acquire-item.cc

@@ -984,6 +984,8 @@ void pkgAcqIndex::Done(string Message,unsigned long long Size,string Hash,
    DestFile += ".decomp";
    Desc.URI = decompProg + ":" + FileName;
    QueueURI(Desc);
+
+   // FIXME: this points to a c++ string that goes out of scope
    Mode = decompProg.c_str();
 }
 									/*}}}*/

apt-pkg/contrib/cmndline.cc

@@ -361,6 +361,7 @@ bool CommandLine::DispatchArg(Dispatch *Map,bool NoMatch)
 void CommandLine::SaveInConfig(unsigned int const &argc, char const * const * const argv)
 {
    char cmdline[100 + argc * 50];
+   memset(cmdline, 0, sizeof(cmdline));
    unsigned int length = 0;
    bool lastWasOption = false;
    bool closeQuote = false;

apt-pkg/contrib/strutl.cc

@@ -943,6 +943,8 @@ bool StrToTime(const string &Val,time_t &Result)
    Tm.tm_isdst = 0;
    if (Month[0] != 0)
       Tm.tm_mon = MonthConv(Month);
+   else
+      Tm.tm_mon = 0; // we don't have a month, so pick something
    Tm.tm_year -= 1900;
    
    // Convert to local time and then to GMT