fuchsia: export VMO only when dedicated image/buffer is available.

Exportable VMOs are created through sysmem BufferCollections
and it requires either dedicated image or dedicated buffer
is provided in VkMemoryDedicatedAllocateInfo.  If neither is
supported, the allocation should fail.

Test: gfx_unittests on ToT goldfish-opengl
Change-Id: I232925f3f2cc9e2d6e38c48ed09c083bb2e48d78
1 file changed