Select correct memory heap index for memory import

Select correct memory heap index for memory import

When importing memory, the application (CTS) should follow
the spec rules about memory imports. I.e. The application must use the
same memory heap index for the import that has been used for the
exported memory. In addition, the application can't
import a buffer or image to a heap that does not support CPU mapping and
expect the memory to be CPU mappable/accessible.

This change modifies the export memory routines, now, returning the
index of the heap memory used for the export. Then the import routines are
modified to use those indexes for the memory import operations.

Components: Vulkan

Affects:
    dEQP-VK.api.external.memory.*
    dEQP-VK.synchronization.cross_instance.*

VK-GL-CTS issue: 585

Change-Id: I48ab85b7fd2b67655163f055fb03e8f2a3a42fd6