Fixed some issues identified by static code analysis.

The following issues were identified and fixed:

 * Allocator sizeof operand mismatch in dbi utils.
 * Dead increment in tools/sysdb/input.
 * Memory leak (and leaving behind invalid memory) in tools/sysdbd/configfile.
 * Out-of-bound array access in core/plugin (the original report by the clang
   analyzer was wrong but pointed to a location affected by a related
   problem).
 * Stack address stored into global variable in liboconfig.

Thanks to cppcheck and the clang analyzer!