all: fix misspellings

Change-Id: I429637ca91f7db4144f17621de851a548dc1ce76
Reviewed-on: https://go-review.googlesource.com/34923
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/database/sql/sql.go

@@ -2086,7 +2086,7 @@ func (rs *Rows) Next() bool {
 		}
 		// The driver is at the end of the current result set.
 		// Test to see if there is another result set after the current one.
-		// Only close Rows if there is no futher result sets to read.
+		// Only close Rows if there is no further result sets to read.
 		if !nextResultSet.HasNextResultSet() {
 			rs.Close()
 		}