Always wait for child processes when forked, even if the process failed.

runtime/bin/process_macos.cc

Index: runtime/bin/process_macos.cc
diff --git a/runtime/bin/process_macos.cc b/runtime/bin/process_macos.cc
index ff9a5245c732445845455cbfea7d3936d02da498..edb222af3fb11acc7037a1f9a813ba374529ea63 100644
--- a/runtime/bin/process_macos.cc
+++ b/runtime/bin/process_macos.cc
@@ -405,6 +405,9 @@ int Process::Start(const char* path,
     ReportChildError(exec_control[1]);
   }
 
+  // Be sure to listen for exit-codes, now we have a child-process.
+  ExitCodeHandler::ProcessStarted();
+
   // The arguments and environment for the spawned process are not needed
   // any longer.
   delete[] program_arguments;
@@ -491,9 +494,6 @@ int Process::Start(const char* path,
   *err = read_err[0];
   VOID_TEMP_FAILURE_RETRY(close(read_err[1]));
 
-  // Be sure to listen for exit-codes, now we have a child-process.
-  ExitCodeHandler::ProcessStarted();
-
   *id = pid;
   return 0;
 }