qtrle.c: Fix for ticket #226.

In 1bpp mode, interpret skip&0x80 as "start a new line" instead of "go to next line", this is almost the same except for the first line which was always skipped before and caused to try to write an extra line at the end of the frame (ticket #226).

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>