WindowServer: unveil("/bin", "x") so we can start applications

Without this, we can't start programs via the system menu. This begs
the question: should WindowServer really be allowed to fork and exec
in the first place?

Servers/WindowServer/main.cpp

@@ -110,6 +110,11 @@ int main(int, char**)
         return 1;
     }
 
+    if (unveil("/bin", "x") < 0) {
+        perror("unveil");
+        return 1;
+    }
+
     if (unveil(nullptr, nullptr) < 0) {
         perror("unveil");
         return 1;