Minor glitch in compiler.cc when compiling with USE_RELAY_DEBUG

[chuck-pilkington]

@icemelon9 :

In tvm/src/relay/backend/vm/compiler.cc, I had to change vm.functions to vm_->functions to get the Compile function to compile:

b6dc78260 (Haichen Shen      2019-07-15 21:02:12 -0700 742) #ifdef USE_RELAY_DEBUG
000000000 (Not Committed Yet 2019-07-17 10:37:34 -0400 743)     for (auto vm_func : vm_->functions) {
b6dc78260 (Haichen Shen      2019-07-15 21:02:12 -0700 744)     std::cout << "Function: " << vm_func.name << std::endl
b6dc78260 (Haichen Shen      2019-07-15 21:02:12 -0700 745)               << vm_func << "-------------" << std::endl;
93d1c06d9 (Wei Chen          2019-07-09 11:48:44 -0700 746)   }
b6dc78260 (Haichen Shen      2019-07-15 21:02:12 -0700 747) #endif  // USE_RELAY_DEBUG