amd-aie-rt fails to cross build from source for two distinct reasons.

The first reason is rooted in its cpputest dependency. That package
depends on a library development package but is itself marked
Multi-Arch: foreign. This is an RC bug and I'm filing it separately. As
a result, the development package is installed for the build
architecture when it is actually needed for the host architecture. As it
happens, amd-aie-rt does not actually need any of the scripts and
examples contained in cpputest. What is contained in libcpputest-dev is
sufficient for building amd-aie-rt, so reducing the dependency helps
with cross building.

The other reason is rooted in the use-system-liburing.patch. It
introduces a use of PKG_CONFIG into the Makefiles driven from the CMake
build system. When debhelper detects CMake, it does not export
PKG_CONFIG and other variables, so liburing is not found. What would be
better here is locating liburing in CMake and linking the detected
library. Rather than fixing the patch, I suggest explicitly exporting
PKG_CONFIG.

The attached patch includes both changes and makes amd-aie-rt cross
buildable. Please consider applying an/or improving it.

Helmut