deal with warnings

@levnach - there are some additional warnings.
You could revert the change to std_vector or use usize() that I added to vector.h. Look at build logs from the pipelines or actions or figure out how to add a continuous AI script to fixup build warnings (I tried a few times earlier on but the features available to do this were not for laymen).

src/nlsat/nlsat_clause.h

@@ -64,7 +64,7 @@ namespace nlsat {
         assumption_set assumptions() const { return m_assumptions; }
     };
 
-    typedef std_vector<clause*> clause_vector;
+    typedef ptr_vector<clause> clause_vector;
 
 };
 

src/nlsat/nlsat_solver.cpp

@@ -804,7 +804,7 @@ namespace nlsat {
             del_clause(cls);
         }
 
-        void del_clauses(std_vector<clause*> & cs) {
+        void del_clauses(clause_vector & cs) {
             for (clause* cp : cs) 
                 del_clause(cp);
             cs.clear();