Description:
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In php_date.c I see some (unsuccessful) effort to calculate proper offset, I mean line

gmt_offset = timelib_get_current_offset(t) / 3600;

but it gets only _main_ zone offset, without current summer time added. I.e. for Europe/Moscow it _always_ gets 3, but in the summer it must be 4.

This code can't work in any case, because it consider 'time' argument only few lines later: 

timelib_unixtime2local(t, time);

but at the moment timelib_get_current_offset(t) called, 'time' arg simple unused, so you can't get summer offset this way, only main one.

Please fix the code to count summer time too,

Reproduce code:
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I have following lines in my php.ini:
date.default_latitude=55.75
date.default_longitude=37.61
date.timezone=Europe/Moscow

and call this test script when summer time (+0400) is active:
<?php
echo date("r").', '.date_sunrise(time()).', '.date_sunset(time());
echo date("r").', '.date_sunrise(time(),SUNFUNCS_RET_STRING,55.75,37.61,90.583333,4).', '.date_sunset(time(),SUNFUNCS_RET_STRING,55.75,37.61,90.583333,4);
?>

Expected result:
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Two echo calls must produce the same sunrise/sunset results when summer Moscow time (GMT+4, specified directly in the second echo call) is active.

Actual result:
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Sunset/sunrise time of the first echo is one hour behind (GMT+3), when script called with summer time active. 
date() call itself reports +0400 properly.
Moreover, I consult astronomical tables, first sunrise/sunset is definitely one hour behind.