[C++ API] Remove best options printing from genetic_search.cc

This allows better decoupling of the genetic search from the backend and
removes the hardwired Cuda dependency.
A generic way of printing the best options was previously added in
autotuner-inl.h but will be activated later.
As a consequence printing of the best option per generation to LOG(INFO)
with the flag --tuner_print_best=1 is temporarily disabled and will be
reactivated when we use the new API.
The printing of the best options per generation can still be activated with
--debug_tuner=1.

Author: nicolasvasilache

tc/autotuner/genetic_search.cc

@@ -302,12 +302,6 @@ void GeneticSearch::updateParameters() {
   // Update failsafe lastBestConf
   lastBestConf =
       population.size() > 0 ? population.front()->configuration : lastBestConf;
-  if (FLAGS_tuner_print_best) {
-    CudaMappingOptions options(
-        CudaMappingOptions::makeSingleThreadMappingOptions());
-    lastBestConf.applyToCudaMappingOptions(options);
-    LOG(INFO) << "Best so far:\n" << options;
-  }
 
   if (population.size() < kMinCandidatesForBreeding) {
     LOG_IF(ERROR, FLAGS_debug_tuner)