Further polish SQLite vendoring

- Now integrated with `make tags` for Emacs IDE features
- Delete some old deprecated broken full-text search engines
- Rename .h → .inc files that don't meet our definition of header
- Make sure every #include line is normal form so tools understand

See #162

third_party/sqlite3/whereexpr.c

@@ -16,8 +16,8 @@
 ** readability and editabiliity.  This file contains utility routines for
 ** analyzing Expr objects in the WHERE clause.
 */
-#include "third_party/sqlite3/sqliteInt.h"
-#include "third_party/sqlite3/whereInt.h"
+#include "third_party/sqlite3/sqliteInt.inc"
+#include "third_party/sqlite3/whereInt.inc"
 /* clang-format off */
 
 /* Forward declarations */