I looked into this bug (Debian bug 177940) and wrote the following patch to mktime.c. Please give it a try. You should be able to apply this patch to libc6's mktime.c.
http://savannah.gnu.org/cgi-bin/viewcvs/gnulib/gnulib/lib/mktime.c.diff?r1=1.36&r2=1.37
