Add a check for EOVERFLOW errno and adjust tm_isdst
Add a check for EOVERFLOW errno and adjust tm_isdst

Checks EOVERFLOW as well for retrying. This way we get correct
timestamp even for times with bogus isdst under NetBSD. Skip
the retry if tm_isdst is already 0. Restore original value of
tm_isdst if retrying also fails. Handle this way both calls
to mktime(), not just the last one.

mlarraz/rubinius,ngpestelos/rubinius,kachick/rubinius,benlovell/rubinius,mlarraz/rubinius,mlarraz/rubinius,ruipserra/rubinius,sferik/rubinius,digitalextremist/rubinius,heftig/rubinius,ngpestelos/rubinius,jemc/rubinius,jemc/rubinius,jsyeo/rubinius,kachick/rubinius,Wirachmat/rubinius,mlarraz/rubinius,ruipserra/rubinius,ngpestelos/rubinius,benlovell/rubinius,kachick/rubinius,dblock/rubinius,dblock/rubinius,dblock/rubinius,benlovell/rubinius,sferik/rubinius,kachick/rubinius,digitalextremist/rubinius,ngpestelos/rubinius,Wirachmat/rubinius,Wirachmat/rubinius,jemc/rubinius,ruipserra/rubinius,pH14/rubinius,sferik/rubinius,heftig/rubinius,jsyeo/rubinius,dblock/rubinius,digitalextremist/rubinius,benlovell/rubinius,dblock/rubinius,jsyeo/rubinius,Wirachmat/rubinius,ngpestelos/rubinius,benlovell/rubinius,heftig/rubinius,jsyeo/rubinius,Wirachmat/rubinius,Azizou/rubinius,benlovell/rubinius,sferik/rubinius,Azizou/rubinius,pH14/rubinius,jemc/rubinius,Wirachmat/rubinius,ngpestelos/rubinius,jsyeo/rubinius,pH14/rubinius,heftig/rubinius,mlarraz/rubinius,jemc/rubinius,ruipserra/rubinius,jsyeo/rubinius,pH14/rubinius,dblock/rubinius,mlarraz/rubinius,digitalextremist/rubinius,jsyeo/rubinius,sferik/rubinius,kachick/rubinius,kachick/rubinius,Azizou/rubinius,ngpestelos/rubinius,pH14/rubinius,heftig/rubinius,heftig/rubinius,sferik/rubinius,ruipserra/rubinius,Azizou/rubinius,dblock/rubinius,benlovell/rubinius,jemc/rubinius,kachick/rubinius,pH14/rubinius,ruipserra/rubinius,digitalextremist/rubinius,Wirachmat/rubinius,digitalextremist/rubinius,kachick/rubinius,jemc/rubinius,Azizou/rubinius,sferik/rubinius,digitalextremist/rubinius,pH14/rubinius,ruipserra/rubinius,mlarraz/rubinius,Azizou/rubinius,Azizou/rubinius,heftig/rubinius