Performance improvements in moveToChild() by shifting some work over

to getAndInitPage().  Net improvement is about 800K cycles at cost of 30 bytes.

FossilOrigin-Name: 1956a4ce8eca650d98a7f68fd2d82eb8a3d6069f

src/btreeInt.h

@@ -518,6 +518,7 @@ struct BtCursor {
   int skipNext;    /* Prev() is noop if negative. Next() is noop if positive.
                    ** Error code if eState==CURSOR_FAULT */
   u8 curFlags;              /* zero or more BTCF_* flags defined below */
+  u8 curPagerFlags;         /* Flags to send to sqlite3PagerAcquire() */
   u8 eState;                /* One of the CURSOR_XXX constants (see below) */
   u8 hints;                             /* As configured by CursorSetHints() */
   i16 iPage;                            /* Index of current page in apPage */