Libraries: Use default constructors/destructors in LibSQL

https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#cother-other-default-operation-rules

"The compiler is more likely to get the default semantics right and
you cannot implement these functions better than the compiler."

Userland/Libraries/LibSQL/AST/AST.h

@@ -1,6 +1,7 @@
 /*
  * Copyright (c) 2021, Tim Flynn <trflynn89@serenityos.org>
  * Copyright (c) 2021, Mahmoud Mandour <ma.mandourr@gmail.com>
+ * Copyright (c) 2022, the SerenityOS developers.
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -29,7 +30,7 @@ create_ast_node(Args&&... args)
 
 class ASTNode : public RefCounted<ASTNode> {
 public:
-    virtual ~ASTNode() { }
+    virtual ~ASTNode() = default;
 
 protected:
     ASTNode() = default;

Userland/Libraries/LibSQL/AST/SyntaxHighlighter.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2021, Dylan Katz <dykatz@uw.edu>
+ * Copyright (c) 2022, the SerenityOS developers.
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -95,8 +96,4 @@ bool SyntaxHighlighter::token_types_equal(u64 token1, u64 token2) const
     return static_cast<TokenType>(token1) == static_cast<TokenType>(token2);
 }
 
-SyntaxHighlighter::~SyntaxHighlighter()
-{
-}
-
 }

Userland/Libraries/LibSQL/AST/SyntaxHighlighter.h

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2021, Dylan Katz <dykatz@uw.edu>
+ * Copyright (c) 2022, the SerenityOS developers.
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -12,8 +13,8 @@ namespace SQL::AST {
 
 class SyntaxHighlighter final : public Syntax::Highlighter {
 public:
-    SyntaxHighlighter() { }
-    virtual ~SyntaxHighlighter() override;
+    SyntaxHighlighter() = default;
+    virtual ~SyntaxHighlighter() override = default;
 
     virtual bool is_identifier(u64) const override;
 

Userland/Libraries/LibSQL/SQLClient.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2021, Jan de Visser <jan@de-visser.net>
+ * Copyright (c) 2022, the SerenityOS developers.
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -8,10 +9,6 @@
 
 namespace SQL {
 
-SQLClient::~SQLClient()
-{
-}
-
 void SQLClient::connected(int connection_id, String const& connected_to_database)
 {
     if (on_connected)

Userland/Libraries/LibSQL/SQLClient.h

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2021, Jan de Visser <jan@de-visser.net>
+ * Copyright (c) 2022, the SerenityOS developers.
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -16,7 +17,7 @@ class SQLClient
     : public IPC::ConnectionToServer<SQLClientEndpoint, SQLServerEndpoint>
     , public SQLClientEndpoint {
     IPC_CLIENT_CONNECTION(SQLClient, "/tmp/portal/sql")
-    virtual ~SQLClient();
+    virtual ~SQLClient() = default;
 
     Function<void(int, String const&)> on_connected;
     Function<void(int)> on_disconnected;