database/sql: fix typo in comment

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/43300043

src/pkg/database/sql/fakedb_test.go

@@ -23,7 +23,7 @@ var _ = log.Printf
 // interface, just for testing.
 //
 // It speaks a query language that's semantically similar to but
-// syntantically different and simpler than SQL.  The syntax is as
+// syntactically different and simpler than SQL.  The syntax is as
 // follows:
 //
 //   WIPE