Avoid using the "direct overflow read" optimization to read large blobs if the

pager layer has a wal file open - even if the database header indicates that
the db is not a wal database.

FossilOrigin-Name: b54c15f11796a75683eec4b502a22ccb87d621c6

src/btree.c

@@ -4608,7 +4608,7 @@ static int accessPayload(
          && (bEnd || a==ovflSize)                              /* (6) */
          && pBt->inTransaction==TRANS_READ                     /* (4) */
          && (fd = sqlite3PagerFile(pBt->pPager))->pMethods     /* (3) */
-         && pBt->pPage1->aData[19]==0x01                       /* (5) */
+         && 0==sqlite3PagerUseWal(pBt->pPager)                 /* (5) */
          && &pBuf[-4]>=pBufStart                               /* (7) */
         ){
           u8 aSave[4];

src/pager.c

@@ -817,9 +817,10 @@ static const unsigned char aJournalMagic[] = {
 ** rollback journal. Otherwise false.
 */
 #ifndef SQLITE_OMIT_WAL
-static int pagerUseWal(Pager *pPager){
+int sqlite3PagerUseWal(Pager *pPager){
   return (pPager->pWal!=0);
 }
+# define pagerUseWal(x) sqlite3PagerUseWal(x)
 #else
 # define pagerUseWal(x) 0
 # define pagerRollbackWal(x) 0

src/pager.h

@@ -178,10 +178,13 @@ int sqlite3PagerSharedLock(Pager *pPager);
   int sqlite3PagerWalCallback(Pager *pPager);
   int sqlite3PagerOpenWal(Pager *pPager, int *pisOpen);
   int sqlite3PagerCloseWal(Pager *pPager, sqlite3*);
+  int sqlite3PagerUseWal(Pager *pPager);
 # ifdef SQLITE_ENABLE_SNAPSHOT
   int sqlite3PagerSnapshotGet(Pager *pPager, sqlite3_snapshot **ppSnapshot);
   int sqlite3PagerSnapshotOpen(Pager *pPager, sqlite3_snapshot *pSnapshot);
 # endif
+#else
+# define sqlite3PagerUseWal(x) 0
 #endif
 
 #ifdef SQLITE_ENABLE_ZIPVFS