condition threadsafe on ENABLE_PTHREAD_SUPPORT

lib/sqlite/sqlite3.c

@@ -366,6 +366,12 @@ SQLITE_PRIVATE   void sqlite3Coverage(int);
 ** Older versions of SQLite used an optional THREADSAFE macro.
 ** We support that for legacy
 */
+#ifdef ENABLE_PTHREAD_SUPPORT
+#define SQLITE_THREADSAFE 1
+#else
+#define SQLITE_THREADSAFE 0
+#endif
+
 #if !defined(SQLITE_THREADSAFE)
 # define SQLITE_THREADSAFE 1
 #endif