Misc: Add a simple init process

This doesn't do much right now, just fork off a bunch of stuff and set priorities.

Servers/SystemServer/main.cpp

@@ -0,0 +1,63 @@
+#include <stdio.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <sched.h>
+#include <AK/Assertions.h>
+
+void start_process(const char *prog, int prio)
+{
+    pid_t pid = 0;
+
+    while (true) {
+        dbgprintf("Forking for %s...\n", prog);
+        int pid = fork();
+        if (pid < 0) {
+            dbgprintf("Fork %s failed! %s\n", prog, strerror(errno));
+            continue;
+        } else if (pid > 0) {
+            // parent...
+            dbgprintf("Process %s hopefully started with priority %d...\n", prog, prio);
+            return;
+        }
+        break;
+    }
+
+    while (true) {
+        if (pid == 0) {
+            dbgprintf("Executing for %s... at prio %d\n", prog, prio);
+            struct sched_param p;
+            p.sched_priority = prio;
+            int ret = sched_setparam(pid, &p);
+            ASSERT(ret == 0);
+
+            char* progv[256];
+            progv[0] = (char*)prog;
+            progv[1] = nullptr;
+            ret = execv(prog, progv);
+            if (ret < 0) {
+                dbgprintf("Exec %s failed! %s", prog, strerror(errno));
+                continue;
+            }
+            break;
+        } else {
+            break;
+        }
+    }
+}
+
+int main(int, char **)
+{
+    int lowest_prio = sched_get_priority_min(SCHED_OTHER);
+    int highest_prio = sched_get_priority_max(SCHED_OTHER);
+    start_process("/bin/LookupServer", lowest_prio);
+    start_process("/bin/WindowServer", highest_prio);
+    start_process("/bin/Taskbar", highest_prio);
+    start_process("/bin/Terminal", highest_prio-1);
+    start_process("/bin/Launcher", highest_prio);
+
+    while (1) {
+        sleep(1);
+    }
+}