build (sparkd): Pipe 'eval' cmd stdout/err back to shell

So we can actually see the build output

tools/build_sparkd.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
 
 tools_path=$(dirname $(readlink -f $0))
-exec "$tools_path/ensure_venv.sh"
+eval "$tools_path/ensure_venv.sh" 1> /dev/stdout 2> /dev/stderr
-exec "$tools_path/venv_exec.sh python $tools_path/py/build_sparkd.py $@"
+eval "$tools_path/venv_exec.sh python $tools_path/py/build_sparkd.py $@" 1> /dev/stdout 2> /dev/stderr