dashboard: build sub-repos on more builders
dashboard: build sub-repos on more builders

Change-Id: I57c12f427448281d71b8507ed950038209134143
Reviewed-on: https://go-review.googlesource.com/10915
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

evandbrown/build,proppy/build,proppy/build,evandbrown/build,golang/build,golang/build,proppy/build,evandbrown/build,golang/build,proppy/build,golang/build