gnu: go-github-com-stretchr-objx: Skip tests with gccgo.

* gnu/packages/golang.scm (go-github-com-stretchr-objx)[arguments]:
Don't run the test suite when building with gccgo.

gnu/packages/golang.scm

@@ -3026,7 +3026,16 @@ Go.")
             (delete-file-recursively "vendor")))))
     (build-system go-build-system)
     (arguments
-     '(#:import-path "github.com/stretchr/objx"))
+     (list
+       #:import-path "github.com/stretchr/objx"
+       #:phases
+       #~(modify-phases %standard-phases
+           (replace 'check
+             (lambda* (#:key inputs #:allow-other-keys #:rest args)
+               (unless
+                 ;; The tests fail when run with gccgo.
+                 (false-if-exception (search-input-file inputs "/bin/gccgo"))
+                 (apply (assoc-ref %standard-phases 'check) args)))))))
     (propagated-inputs
      (list go-github-com-davecgh-go-spew
            go-github-com-pmezard-go-difflib))