Make compilation less noisy

Based on Douglas Gilbert's notice:

smartd.cpp:740: warning: format not a string literal and no format arguments
smartd.cpp:1369: warning: ignoring return value of int dup(int)
smartd.cpp:1371: warning: ignoring return value of int dup(int)
smartd.cpp:1373: warning: ignoring return value of int chdir(const char*)
smartd.cpp:3742: warning: format not a string literal and no format arguments


git-svn-id: https://smartmontools.svn.sourceforge.net/svnroot/smartmontools/trunk@2722 4ea69e1a-61f1-4043-bf83-b5c94c648137