Fix the way submodules are detected by the top cmake script.
Fix the way submodules are detected by the top cmake script.

d-das/cpp-ethereum,LefterisJP/cpp-ethereum,xeddmc/cpp-ethereum,d-das/cpp-ethereum,joeldo/cpp-ethereum,LefterisJP/cpp-ethereum,d-das/cpp-ethereum,expanse-org/cpp-expanse,gluk256/cpp-ethereum,LefterisJP/cpp-ethereum,d-das/cpp-ethereum,xeddmc/cpp-ethereum,expanse-org/cpp-expanse,expanse-org/cpp-expanse,xeddmc/cpp-ethereum,karek314/cpp-ethereum,vaporry/webthree-umbrella,programonauta/webthree-umbrella,karek314/cpp-ethereum,joeldo/cpp-ethereum,LefterisJP/cpp-ethereum,expanse-org/cpp-expanse,xeddmc/cpp-ethereum,joeldo/cpp-ethereum,joeldo/cpp-ethereum,gluk256/cpp-ethereum,LefterisJP/cpp-ethereum,gluk256/cpp-ethereum,expanse-org/cpp-expanse,karek314/cpp-ethereum,gluk256/cpp-ethereum,LefterisJP/webthree-umbrella,karek314/cpp-ethereum,gluk256/cpp-ethereum,d-das/cpp-ethereum,arkpar/webthree-umbrella,karek314/cpp-ethereum,chfast/webthree-umbrella,programonauta/webthree-umbrella,LefterisJP/cpp-ethereum,karek314/cpp-ethereum,xeddmc/cpp-ethereum,d-das/cpp-ethereum,xeddmc/cpp-ethereum,expanse-org/cpp-expanse,gluk256/cpp-ethereum,joeldo/cpp-ethereum,joeldo/cpp-ethereum,LefterisJP/webthree-umbrella