[SECURITY] [DLA 117-1] qt4-x11 security update

Package : qt4-x11
Version : 4:4.6.3-4+squeeze2
CVE ID : CVE-2011-3193 CVE-2011-3194

CVE-2011-3193

Check for buffer overflow in Lookup_MarkMarkPos that may cause crash
in this function with certain fonts.

CVE-2011-3194

Fix tiff reader to handle TIFFTAG_SAMPLESPERPIXEL for grayscale
images. The reader uses QImage::Format_Indexed8, but since the samples
per pixel value this should be (non-existent) QImage::Format_Indexed16,
causing memory corruption. The fix falls back to the "normal" way of
reading tiff images.