glsl/types: Ignore bit sizes in contains_integer()

All of the callers for this function are looking at interpolation
qualifiers and want to make sure they're declared flat.  Any 64-bit
integer inputs need to be flat.  It's also makes the function make more
sense since "integer" is fairly generic.

Reviewed-by: Karol Herbst <kherbst@redhat.com>

src/compiler/glsl_types.cpp

@@ -246,7 +246,7 @@ glsl_type::contains_integer() const
       }
       return false;
    } else {
-      return this->is_integer();
+      return glsl_base_type_is_integer(this->base_type);
    }
 }