LibELF+Userland: Enable RELRO for all userland executables :^)

The dynamic loader will now mark RELRO segments read-only after
performing relocations. This is pretty cool!

Note that this only applies to main executables so far,.
RELRO support for shared libraries will require some reorganizing
of the dynamic loader.

Userland/Libraries/LibELF/DynamicObject.cpp

@@ -160,6 +160,9 @@ void DynamicObject::parse()
             m_soname_index = entry.val();
             m_has_soname = true;
             break;
+        case DT_BIND_NOW:
+            m_dt_flags |= DF_BIND_NOW;
+            break;
         case DT_DEBUG:
             break;
         case DT_FLAGS_1: