x11: x and xv image pool don't propagate the AllocationParams

Submitted by Nicolas Dufresne @ndufresne

Link to original bug (#749038)

Description

Current, X and XV image pool don't propagate the allocation params (only the video alignment). This may lead to error or crash in with some optimized code that may require a certain alignment. Note that this have not cause much issue, since by for shared memory, the default alignment is 16 (which is usually what optimize code need), but if SHM does not work, it's what g_malloc() do.