khttp_fcgi_test with variable worker pool

[causal-agent]

khttp_fcgi_test(3) returns 0 rather than 1 when using a kfcgi(8) variable-sized worker pool:

#include <stdio.h>
#include <sys/types.h>
#include <stdarg.h>
#include <stdint.h>
#include <kcgi.h>
int main(void) {
    printf("%d\n", khttp_fcgi_test());
}

$ freebsd-version
12.0-RELEASE
$ pkg info -o kcgi
kcgi-0.12.1                    www/kcgi
$ sudo kfcgi -d -s test.sock -p $PWD -n 1 -- ./repro
1
kfcgi 57318 - - worker unexpectedly exited
$ sudo kfcgi -d -s test.sock -p $PWD -r -n 1 -- ./repro
0
kfcgi 57321 - - worker unexpectedly exited