Log Message:
Update go115 to 1.15.10.

go1.15.8 (released 2021/02/04) includes fixes to the compiler, linker, runtime,
the go command, and the net/http package. See the Go 1.15.8 milestone on our
issue tracker for details.

go1.15.9 (released 2021/03/10) includes security fixes to the encoding/xml
package. See the Go 1.15.9 milestone on our issue tracker for details.

go1.15.10 (released 2021/03/11) includes fixes to the compiler, the go command,
and the net/http, os, syscall, and time packages. See the Go 1.15.10 milestone
on our issue tracker for details.