Debugger: Add some pledges required by LibLine

These are a bit unfortunate. We should reorganize LibLine so it sets
up the RPC server earlier, then we can drop these pledges later on.

Applications/Debugger/main.cpp

@@ -174,7 +174,7 @@ int main(int argc, char** argv)
 {
     editor = Line::Editor::construct();
 
-    if (pledge("stdio proc exec rpath tty sigaction", nullptr) < 0) {
+    if (pledge("stdio proc exec rpath tty sigaction cpath unix fattr", nullptr) < 0) {
         perror("pledge");
         return 1;
     }