[sql] Import reference version of SQLite 3.7.6.3.

third_party/sqlite/sqlite-src-3070603/src/loadext.c

 /*
 ** 2006 June 7
 **
 ** The author disclaims copyright to this source code.  In place of
 ** a legal notice, here is a blessing:
 **
 **    May you do good and not evil.
 **    May you find forgiveness for yourself and forgive others.
 **    May you share freely, never taking more than you give.
 **
@@ skipping 630 matching lines @@
     sqlite3_mutex_leave(mutex);
     zErrmsg = 0;
     if( xInit && xInit(db, &zErrmsg, &sqlite3Apis) ){
       sqlite3Error(db, SQLITE_ERROR,
             "automatic extension loading failed: %s", zErrmsg);
       go = 0;
     }
     sqlite3_free(zErrmsg);
   }
 }