Fix permissions for installation of OMSimulator exes. (#9670)

  - We install them using the DIRECTORY specifier which does not give them
    the needed permissions to execute. Use source permissions explicitly.

    There is still some inconsistency in what permission OMSimulator sets
    for its executables. This should be fixed because it can lead to some
    confusing errors where some executables run fine while others fail.

omsimulator.cmake

@@ -92,7 +92,8 @@ else()
 
 
   install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/OMSimulator/bin/
-          DESTINATION ${CMAKE_INSTALL_BINDIR})
+          DESTINATION ${CMAKE_INSTALL_BINDIR}
+          USE_SOURCE_PERMISSIONS)
 
 
   install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/OMSimulator/include/