reduce set of mainly verbose warnings raised by -Wmaybe-uninitialized and unused variable warnings from release mode builds

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/ast/normal_forms/pull_quant.cpp

@@ -58,7 +58,7 @@ struct pull_quant::imp {
             }
             
             bool found_quantifier = false;
-            bool forall_children;
+            bool forall_children = false;
             
             for (unsigned i = 0; i < num_children; i++) {
                 expr * child = children[i];