[config] fix 32bit build
[config] fix 32bit build

This is to fix build error in
https://ci.chromium.org/p/infra-internal/builders/prod/infra-packager-win-32/6542
# go.chromium.org/luci/gce/api/config/v1
..\cache\infra_gclient_with_go\infra\go\src\go.chromium.org\luci\gce\api\config\v1\duration.go:38:27: constant 9223372036854775807 overflows int


Change-Id: I586d1045e7a3ff762cb7a03a95dcc35c8f7b36f4
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/1585560
Auto-Submit: Takuto Ikuta <71927f930fca81015e0f496c65cd126ab1a692e3@chromium.org>
Reviewed-by: Andrii Shyshkalov <a30c74fa30536fe7ea81ed6dec202e35e149e1fd@chromium.org>
Commit-Queue: Andrii Shyshkalov <a30c74fa30536fe7ea81ed6dec202e35e149e1fd@chromium.org>

luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go