Skip a GC test known to be flaky:

  https://issues.guix.gnu.org/issue/37425
  https://github.com/golang/go/issues/27636

--- go/src/runtime/gc_test.go	2019-09-16 23:10:18.200680387 +0200
+++ go/src/runtime/gc_test.go	2019-09-16 23:11:50.324360646 +0200
@@ -27,6 +27,9 @@ func TestGcSys(t *testing.T) {
 	if runtime.GOOS == "linux" && runtime.GOARCH == "arm64" {
 		t.Skip("skipping test; GOOS=linux GOARCH=arm64 https://github.com/golang/go/issues/27636")
 	}
+	if runtime.GOOS == "linux" {
+		t.Skip("skipping test; GOOS=linux https://issues.guix.gnu.org/issue/37425")
+	}
 	got := runTestProg(t, "testprog", "GCSys")
 	want := "OK\n"
 	if got != want {
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<tr><td><span title='2021-05-20 01:58:04 +0200'>2021-05-20</span></td><td><a href='/guix/commit/README?id=c0087d33705f53cc3619a1a43a33602aaecc3a8b'>The #guix channel is hosted by Libera Chat.</a><span class='msg-avail'>...<span class='msg-tooltip'>* README (Contact): Update network name.
* ROADMAP: Likewise.
* doc/contributing.texi (Contributing): Likewise.
* doc/guix.texi (After System Installation): Likewise.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-10-23 12:57:20 -0400'>2020-10-23</span></td><td><a href='/guix/commit/README?id=b5aaa3a4fb985d21e21e2a67f48b52f13ebd4728'>doc: Update README.</a><span class='msg-avail'>...<span class='msg-tooltip'>* README (Installation): Do not mention installing Guix from Git anymore.
(Building from Git): Add section.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2020-10-22 22:47:54 -0400'>2020-10-22</span></td><td><a href='/guix/commit/README?id=503d2bfde08f9bf97bbf430516d2f19faedd4319'>README: Refer to the manual for building from Git.</a><span class='msg-avail'>...<span class='msg-tooltip'>* README (Installing Guix from Guix): Remove section.
(Installation): For installing from Git, refer to the "Building from Git"
section of the manual and suggest using './pre-inst-env guix pull' rather than
'make install' for installing Guix.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2020-06-02 18:55:53 +0200'>2020-06-02</span></td><td><a href='/guix/commit/README?id=c75a80189fc19f6ff8b4c82d1d1801be6763b6d2'>doc: Update README to refer to the manual.</a><span class='msg-avail'>...<span class='msg-tooltip'>* README (Requirements): Refer to the manual.
(Installation): Update URL of the manual.
</span></span></td><td>Ludovic Courtès</td></tr>