Add sqlite3 support to Emacs

* configure.ac: Add check for the sqlite library.
* doc/lispref/text.texi (Database): Document it.

* lisp/sqlite.el: New file.

* lisp/term/w32-win.el (dynamic-library-alist): Add a mapping.

* src/Makefile.in (SQLITE3_LIBS): Add the libraries.

* src/alloc.c (union emacs_align_type): Add a Lisp_Sqlite struct.

* src/data.c (Ftype_of): Add sqlite.

* src/emacs.c (main): Load the syms.

* src/lisp.h (DEFINE_GDB_SYMBOL_BEGIN): Add PVEC_SQLITE.
(GCALIGNED_STRUCT): New struct to keep data for sqlite database
objects and statement objects.
(SQLITEP, SQLITE, CHECK_SQLITE, XSQLITE): New macros for accessing
the objects.

* src/pdumper.c (dump_vectorlike): Update hash.
(dump_vectorlike): Don't dump it.

* src/print.c (print_vectorlike): Add a printer for the sqlite
object.

* src/sqlite.c: New file.

* test/src/sqlite-tests.el: Add tests.

lisp/sqlite.el

@@ -0,0 +1,42 @@
+;;; sqlite.el --- Tests for empty.el  -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2021 Free Software Foundation, Inc.
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;;
+
+;;; Code:
+
+(defmacro with-sqlite-transaction (db &rest body)
+  "Execute BODY while holding a transaction for DB."
+  (declare (indent 1) (debug (form body)))
+  (let ((db-var (gensym)))
+    `(let ((,db-var ,db))
+       (if (sqlite-available-p)
+           (unwind-protect
+               (progn
+                 (sqlite-transaction ,db-var)
+                 ,@body)
+             (sqlite-commit ,db-var))
+         (progn
+           ,@body)))))
+
+(provide 'sqlite)
+
+;;; sqlite.el ends here