Add support for the emulation version of the cudart library.

In version 3.0 of the CUDA toolkit when building code for emulation, you need to link
against a new version of the cuda run time library called cudartemu.  This CL adds a check
for the new library and uses it when present and in emulation mode.  Note that this
library is not present in previous or subsequent versions of the CUDA toolkit.

Modules/FindCUDA.cmake

@@ -418,6 +418,10 @@ if(NOT "${CUDA_TOOLKIT_ROOT_DIR}" STREQUAL "${CUDA_TOOLKIT_ROOT_DIR_INTERNAL}")
   unset(CUDA_VERSION CACHE)
   unset(CUDA_TOOLKIT_INCLUDE CACHE)
   unset(CUDA_CUDART_LIBRARY CACHE)
+  if(CUDA_VERSION VERSION_EQUAL "3.0")
+    # This only existed in the 3.0 version of the CUDA toolkit
+    unset(CUDA_CUDARTEMU_LIBRARY CACHE)
+  endif()
   unset(CUDA_CUDA_LIBRARY CACHE)
   unset(CUDA_cublas_LIBRARY CACHE)
   unset(CUDA_cublasemu_LIBRARY CACHE)
@@ -545,11 +549,28 @@ endmacro()
 
 # CUDA_LIBRARIES
 find_library_local_first(CUDA_CUDART_LIBRARY cudart "\"cudart\" library")
-set(CUDA_LIBRARIES ${CUDA_CUDART_LIBRARY})
+if(CUDA_VERSION VERSION_EQUAL "3.0")
+  # The cudartemu library only existed for the 3.0 version of CUDA.
+  find_library_local_first(CUDA_CUDARTEMU_LIBRARY cudartemu "\"cudartemu\" library")
+  mark_as_advanced(
+    CUDA_CUDARTEMU_LIBRARY
+    )
+endif()
+# If we are using emulation mode and we found the cudartemu library then use
+# that one instead of cudart.
+if(CUDA_BUILD_EMULATION AND CUDA_CUDARTEMU_LIBRARY)
+  set(CUDA_LIBRARIES ${CUDA_CUDARTEMU_LIBRARY})
+else()
+  set(CUDA_LIBRARIES ${CUDA_CUDART_LIBRARY})
+endif()
 if(APPLE)
   # We need to add the path to cudart to the linker using rpath, since the
   # library name for the cuda libraries is prepended with @rpath.
-  get_filename_component(_cuda_path_to_cudart "${CUDA_CUDART_LIBRARY}" PATH)
+  if(CUDA_BUILD_EMULATION AND CUDA_CUDARTEMU_LIBRARY)
+    get_filename_component(_cuda_path_to_cudart "${CUDA_CUDARTEMU_LIBRARY}" PATH)
+  else()
+    get_filename_component(_cuda_path_to_cudart "${CUDA_CUDART_LIBRARY}" PATH)
+  endif()
   if(_cuda_path_to_cudart)
     list(APPEND CUDA_LIBRARIES -Wl,-rpath "-Wl,${_cuda_path_to_cudart}")
   endif()