Use of uninitialized local in SR_initialize after JDK-8314114

After JDK-8314114, SonarCloud reports the use on uninitialized `sig` variable in the `warning` line here:
 
int SR_initialize() {
...
    int sig;
    bool result = parse_integer(s, &sig);
    if (result && sig > MAX2(SIGSEGV, SIGBUS) && // See 4355769.
        sig < NSIG) { // Must be legal signal and fit into sigflags[].
      PosixSignals::SR_signum = sig;
    } else {
      warning("You set _JAVA_SR_SIGNUM=%d. It must be in range [%d, %d]. Using %d instead.",
              sig, MAX2(SIGSEGV, SIGBUS)+1, NSIG-1, PosixSignals::SR_signum);
    }