crypto/tls: improve error log produced during TestBogoSuite

The existing implementation logs some errors to the results file created in TestBogoSuite.
This change would additionally log json errors to the results file.

Change-Id: Ib1a6f612ed83f6c5046531ee259c4e85dd71402a
Reviewed-on: https://go-review.googlesource.com/c/go/+/591379
Reviewed-by: Filippo Valsorda <[email protected]>
Auto-Submit: Filippo Valsorda <[email protected]>
Reviewed-by: Roland Shoemaker <[email protected]>
Reviewed-by: Michael Pratt <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: Clide Stefani

src/crypto/tls/bogo_shim_test.go

@@ -368,7 +368,7 @@ func TestBogoSuite(t *testing.T) {
 		if err != nil {
 			t.Fatalf("bogo failed: %s\n%s", err, out)
 		}
-		t.Fatalf("failed to read results JSON file: %s", err)
+		t.Fatalf("failed to read results JSON file: %s", jsonErr)
 	}
 
 	var results bogoResults