go: skip flaky os/exec TestExtraFiles

This seems to only happen on i686 on go 1.11. It also happens on
Debian. For more information:

https://github.com/golang/go/issues/25628

pkgs/development/compilers/go/1.11.nix

@@ -125,6 +125,7 @@ stdenv.mkDerivation rec {
     ./remove-fhs-test-references.patch
     ./skip-external-network-tests.patch
     ./skip-nohup-tests.patch
+    ./skip-test-extra-files-on-386.patch
   ];
 
   postPatch = optionalString stdenv.isDarwin ''

pkgs/development/compilers/go/skip-test-extra-files-on-386.patch

@@ -0,0 +1,15 @@
+diff --git a/src/os/exec/exec_test.go b/src/os/exec/exec_test.go
+index 558345ff63..22129bf022 100644
+--- a/src/os/exec/exec_test.go
++++ b/src/os/exec/exec_test.go
+@@ -593,6 +593,10 @@ func TestExtraFiles(t *testing.T) {
+ 		t.Skipf("skipping test on %q", runtime.GOOS)
+ 	}
+ 
++	if runtime.GOOS == "linux" && runtime.GOARCH  == "386" {
++		t.Skipf("skipping test on %q %q", runtime.GOARCH, runtime.GOOS)
++	}
++
+ 	// Ensure that file descriptors have not already been leaked into
+ 	// our environment.
+ 	if !testedAlreadyLeaked {