Convert to SQLite amalgamation.

third_party/sqlite/src/src/sqlite3ext.h

Index: third_party/sqlite/src/src/sqlite3ext.h
diff --git a/third_party/sqlite/src/src/sqlite3ext.h b/third_party/sqlite/src/src/sqlite3ext.h
index 86d119d7ce2faa0ffa2b83f930494aadb1e19d4c..5526646646c04d20a307d128bd8b9182711f74d9 100644
--- a/third_party/sqlite/src/src/sqlite3ext.h
+++ b/third_party/sqlite/src/src/sqlite3ext.h
@@ -372,15 +372,9 @@ struct sqlite3_api_routines {
 #define sqlite3_next_stmt              sqlite3_api->next_stmt
 #define sqlite3_sql                    sqlite3_api->sql
 #define sqlite3_status                 sqlite3_api->status
+#endif /* SQLITE_CORE */
 
 #define SQLITE_EXTENSION_INIT1     const sqlite3_api_routines *sqlite3_api = 0;
 #define SQLITE_EXTENSION_INIT2(v)  sqlite3_api = v;
 
-#else
-
-#define SQLITE_EXTENSION_INIT1
-#define SQLITE_EXTENSION_INIT2(v)
-
-#endif /* SQLITE_CORE */
-
 #endif /* _SQLITE3EXT_H_ */