Ignore std::vector<T>::get_allocator()

This is not really useful in C wrappers and results in ugly descriptor for the
allocator type appearing in the output, better to avoid it.

Lib/c/std_vector.i

@@ -4,6 +4,9 @@
     void set(size_type n, const value_type& val) { self->at(n) = val; }
     value_type get(size_type n) const { return self->at(n); }
   }
+
+  // Standard typemaps wrap get_allocator(), but it's not really useful for us, so don't bother with it.
+  %ignore get_allocator
 %enddef
 
 %define %swig_vector_methods_val(Type...)