fix: error for constraints with same handle

[DavePearce]

Constraints in the same module with the same handle do not result in an error in some cases (when they are in different source files).

Example 1

For example:

test_a.lisp

(defcolumns (X :i16) (Y :i16))
(defclookup test (Y) 1 (X))

test_b.lisp

(defclookup test (X) 1 (Y))

In this case, there is no error reported.

Example 2

A simpler example is the following:

(module m1)
(defcolumns (X :i16) (Y :i16))
(defclookup test (Y) 1 (X))

(module m1)
(defclookup test (X) 1 (Y))