Add gettimeofday() syscall and LibC wrappers gettimeofday() and time().

This only has second accuracy right now, I'll work out subseconds later.

Userland/date.cpp

@@ -0,0 +1,10 @@
+#include <LibC/time.h>
+#include <LibC/stdio.h>
+
+int main(int c, char** v)
+{
+    time_t now = time(nullptr);
+    printf("%u\n", now);
+    return 0;
+}
+