gdk-pixbuf 2.36.2 release.

• Remove the pixdata loader (#776004)
• Fix integer overflows in the jpeg loader (#775218)
• Add an external thumbnailer for images
• Fix a NULL pointer dereference (#776026)
• Fix a memory leak (#776020)
• Support bmp headers with bitmask (#766890)
• Add tests for scaling (#80925)
• Handle compressed pixdata in resources (#776105)
• Avoid a buffer overrun in the qtif loader ($#775648)
• Fix a crash in the bmp loader (#775242)
• Fix crash opening pnm images with large dimensions (#775232)
• Prevent buffer overflow in the pixdata loader (#775693)
• Translation updates