getopt: fix memory leaks and integer overflows [ASAN & valgrind]

getopt: fix memory leaks and integer overflows [ASAN & valgrind]

The getopt(1) is short living command, and one could argue ensuring all
allocations are freed at end of execution is waste of time.  There is a
point in that, but making test-suite runs to be less noisy with ASAN is also
nice as it encourages reading the errors when/if they happen.

Reviewed-by: Yuriy M. Kaminskiy <yumkam@gmail.com>
Reviewed-by: Karel Zak <kzak@redhat.com>
Signed-off-by: Sami Kerola <kerolasa@iki.fi>