LibTLS: Remove all uses of VLAs

Author: https://github.com/alimpfard
Commit: 98ecb95709
Pull-request: https://github.com/SerenityOS/serenity/pull/7074
Issue: https://github.com/SerenityOS/serenity/issues/7071

Userland/Libraries/LibTLS/Handshake.cpp

@@ -141,7 +141,7 @@ ByteBuffer TLSv12::build_finished()
     PacketBuilder builder { MessageType::Handshake, m_context.options.version, 12 + 64 };
     builder.append((u8)HandshakeType::Finished);
 
-    u32 out_size = 12;
+    constexpr u32 out_size = 12;
 
     builder.append_u24(out_size);