core: remove unnecessary goto in setup_namespace
systemd-analyze: do not format timestamp when not printing it

../src/analyze/systemd-analyze.c:530:88: warning: data argument not used by format string [-Wformat-extra-args]
  ...svg_text(false, u->ixt, y, u->time? "%s (%s)" : "%s", u->name, format_timespan(ts, sizeof(ts), u->time));
                                                     ~~~~           ^
Remove some unused variables
Make two functions static
activate: avoid warning from -Wshadow

src/activate/activate.c:167:51: warning: declaration shadows a variable in the global scope [-Wshadow]
static int launch(char* name, char **argv, char **environ, int fds) {
                                                  ^
/usr/include/unistd.h:546:15: note: previous declaration is here
extern char **environ;
              ^