Tests: Teach RunCMake infrastructure to use custom check.cmake file

Tests/RunCMake/RunCMake.cmake

@@ -115,7 +115,11 @@ function(run_cmake test)
     endif()
   endforeach()
   unset(RunCMake_TEST_FAILED)
-  include(${top_src}/${test}-check.cmake OPTIONAL)
+  if(RunCMake-check-file AND EXISTS ${top_src}/${RunCMake-check-file})
+    include(${top_src}/${RunCMake-check-file})
+  else()
+    include(${top_src}/${test}-check.cmake OPTIONAL)
+  endif()
   if(RunCMake_TEST_FAILED)
     set(msg "${RunCMake_TEST_FAILED}\n${msg}")
   endif()