json: fix trailing space in base64 data

golang/go@20d745c made encoding/base64 pickier about trailing data
such as the extra space at the end of the json base64 data. As a
result, bench now panics with an "unexpected EOF" when starting (even
if you're not running the json benchmark, since this happens at init
time).

Fix this by removing the trailing space.

Change-Id: I312ca0def3bb295c1f19a6ebdaf136ce27591da9
Reviewed-on: https://go-review.googlesource.com/18530
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
diff --git a/json/json_data.go b/json/json_data.go
index 30024f2..689b92b 100644
--- a/json/json_data.go
+++ b/json/json_data.go
@@ -1807,4 +1807,4 @@
 cZ9UZZJyYojLjaeJHfJU1UZUEmBfLumu8yW5skuyE9uh2BmVxJZi6KxaXBNwSolw
 BqBcQLj3ucNZIYZLYtirLu3brW6UYgZgZJiDIGiwpsgg7g1AITkgM6FHITxDDnGt
 4SDHzZbL5s8fec5PCq5DOzDRdWS+0h5Y2INZak1D29cpVyb2aVrV3Wlt7rQhLa3e
-m3ZwPNcXywE2Qesk1XN24HvZ2Xa6nlm8Pf/xdyRThQkO1NjuAA== `)
+m3ZwPNcXywE2Qesk1XN24HvZ2Xa6nlm8Pf/xdyRThQkO1NjuAA==`)