bin: Added kall as a killall5 alternative.

This way we remove the dependency on killall5 and
its basic functionality while at the same time
making our init base more portable across diffeent
init systems.

The name and usage differs so as to not conflict
in any way with killall5 via usage or assumption.

bin/kall.c

@@ -0,0 +1,35 @@
+#define _POSIX_SOURCE
+#include <dirent.h>
+#include <inttypes.h>
+#include <unistd.h>
+#include <signal.h>
+#include <stdio.h>
+
+int main(int argc, char *argv[]) {
+    struct dirent *ent;
+    DIR *dir;
+    int pid, sig = SIGTERM;
+
+    if (argc > 1)
+        sig = strtoimax(argv[1], 0, 10);
+
+    if (!(dir = opendir("/proc")))
+        return 1;
+
+    kill(-1, SIGSTOP);
+
+    while ((ent = readdir(dir))) {
+        pid = strtoimax(ent->d_name, 0, 10);
+
+        if (pid < 2 || pid == getpid() ||
+            getsid(pid) == getsid(0) || getsid(pid) == 0)
+            continue;
+
+        kill(pid, sig);
+    }
+    closedir(dir);
+
+    kill(-1, SIGCONT);
+
+    return 0;
+}