gnu: go-golang-org-x-sync: Simplify

* gnu/packages/golang-build.scm (go-golang-org-x-sync)
[arguments] <skip-build?>: Set to #t, as no go files in project's root.
<phases>: Use default 'check.

Change-Id: Iebc123fd8c103d6d610cc037bb034cb75bb795e3

gnu/packages/golang-build.scm

@@ -732,17 +732,8 @@ loading algorithms.")
     (build-system go-build-system)
     (arguments
      (list
-      #:import-path "golang.org/x/sync"
-      #:phases
-      #~(modify-phases %standard-phases
-          ;; XXX: Workaround for go-build-system's lack of Go modules
-          ;; support.
-          (delete 'build)
-          (replace 'check
-            (lambda* (#:key tests? import-path #:allow-other-keys)
-              (when tests?
-                (with-directory-excursion (string-append "src/" import-path)
-                  (invoke "go" "test" "-v" "./..."))))))))
+      #:skip-build? #t
+      #:import-path "golang.org/x/sync"))
     (home-page "https://go.googlesource.com/sync/")
     (synopsis "Additional Go concurrency primitives")
     (description