analyze: 'unbound-variable' warning handles re-exported bindings.

Fixes <https://bugs.gnu.org/47031>.

* module/language/tree-il/analyze.scm (make-use-before-definition-analysis)
[resolve]: Add case for when NAME is re-exported by MOD.
* test-suite/tests/tree-il.test ("warnings")["re-exported binding"]: New test.

module/language/tree-il/analyze.scm

@@ -510,6 +510,11 @@ given `tree-il' element."
            ;; The variable is an import.  At the time of use, the
            ;; name is bound to the import.
            'import)
+          ((and=> (module-public-interface mod)
+                  (lambda (interface)
+                    (module-variable interface name)))
+           ;; The variable is re-exported from another module.
+           'import)
           (else
            ;; Variable unbound in the module.
            'unbound))))))

test-suite/tests/tree-il.test

@@ -578,6 +578,19 @@
                                         #:env m
                                         #:opts %opts-w-unbound))))))))
 
+   (pass-if "re-exported binding"          ;<https://bugs.gnu.org/47031>
+     (null? (call-with-warnings
+             (lambda ()
+               (compile '(begin
+                           (use-modules (srfi srfi-35))
+
+                           ;; This 'condition' form expands to a
+                           ;; 'make-compound-condition' call, which is
+                           ;; re-exported from (ice-9 exceptions).
+                           (condition (&error)
+                                      (&message (message "oh!"))))
+                        #:opts %opts-w-unbound)))))
+
    (with-test-prefix "use-before-definition"
      (define-syntax-rule (pass-if-warnings expr pat test)
        (pass-if 'expr