The expression list on the RHS of an IN operator can no longer be empty
because an empty expression list is now optimized out by changes in
check-in [c288ac644d0bf].  Therefore add ALWAYS() macros around tests
for the expression list being non-empty.

FossilOrigin-Name: fd130ae56c0e23f2d5b4a82f1a09e89ed7ae1e85
diff --git a/src/expr.c b/src/expr.c
index 8ddf473..2046433 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -1635,7 +1635,7 @@
           keyInfo.aColl[0] = sqlite3BinaryCompareCollSeq(pParse, pExpr->pLeft,
               pEList->a[0].pExpr);
         }
-      }else if( pExpr->x.pList!=0 ){
+      }else if( ALWAYS(pExpr->x.pList!=0) ){
         /* Case 2:     expr IN (exprlist)
         **
         ** For each expression, build an index key from the evaluation and