Log Message:
Update go112 to 1.12.4.

go1.12.2 (released 2019/04/05) includes fixes to the compiler, the go command,
the runtime, and the doc, net, net/http/httputil, and os packages. See the Go
1.12.2 milestone on our issue tracker for details.

go1.12.3 (released 2019/04/08) was accidentally released without its intended
fix. It is identical to go1.12.2, except for its version number. The intended
fix is in go1.12.4.

go1.12.4 (released 2019/04/11) fixes an issue where using the prebuilt binary
releases on older versions of GNU/Linux led to failures when linking programs
that used cgo. Only Linux users who hit this issue need to update.