fix build warnings

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

Author: NikolajBjorner

src/ast/ast.cpp

@@ -1914,7 +1914,7 @@ app * ast_manager::mk_app(family_id fid, decl_kind k, unsigned num_args, expr *
 }
 
 app * ast_manager::mk_app(family_id fid, decl_kind k, std::span<expr* const> args) {
-    return mk_app(fid, k, 0, nullptr, args.size(), args.data());
+    return mk_app(fid, k, 0, nullptr, static_cast<unsigned>(args.size()), args.data());
 }
 
 app * ast_manager::mk_app(family_id fid, decl_kind k, expr * arg) {

src/util/util.h

@@ -362,7 +362,7 @@ class random_gen {
 
 template<typename T>
 void shuffle(std::span<T> array, random_gen & gen) {
-    int n = array.size();
+    auto n = array.size();
     while (--n > 0) {
         int k = gen() % (n + 1);
         std::swap(array[n], array[k]);