strconv: simplify the text for bases in ParseInt
strconv: simplify the text for bases in ParseInt

Followon from a review comment in https://golang.org/cl/191078

Change-Id: If115b2ae0df5e5cb9babd60802947ddb687d56c2
Reviewed-on: https://go-review.googlesource.com/c/go/+/191219
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

cloudflare/go,cloudflare/go,cloudflare/go,akutz/go,akutz/go,akutz/go,nawawi/go,akutz/go,nawawi/go,nawawi/go,golang/go,golang/go,golang/go,CAFxX/go,golang/go,akutz/go,cloudflare/go,golang/go,cloudflare/go,CAFxX/go,akutz/go,nawawi/go,akutz/go,CAFxX/go,CAFxX/go,CAFxX/go,nawawi/go,CAFxX/go,golang/go,CAFxX/go,CAFxX/go,cloudflare/go,nawawi/go,golang/go,cloudflare/go,nawawi/go,cloudflare/go,golang/go,akutz/go,nawawi/go