Reset dependency file list when a dependency disappeared.

Fix a long outstanding bug when a file in the dependency list wasn't found.  This bug
wouldn't reset the dependencies, so the makefile would still want the missing file when
building.  The work around was to configure twice, but this is no longer necessary.

Modules/FindCUDA.cmake

@@ -339,6 +339,8 @@ macro(CUDA_INCLUDE_NVCC_DEPENDENCIES dependency_file)
   # output depend on the dependency file itself, which should cause the
   # rule to re-run.
   if(CUDA_NVCC_DEPEND_REGENERATE)
+    set(CUDA_NVCC_DEPEND ${dependency_file})
+    #message("Generating an empty dependency_file: ${dependency_file}")
     file(WRITE ${dependency_file} "#FindCUDA.cmake generated file.  Do not edit.\n")
   endif(CUDA_NVCC_DEPEND_REGENERATE)