dashboard: set GOARCH and GOHOSTARCH explicitly for mips builders

They're running the 32-bit versions on 64-bit hardware.

Change-Id: I365aa2b77cd729484d49aaefed12737c657abed8
Reviewed-on: https://go-review.googlesource.com/33010
Reviewed-by: Cherry Zhang <cherryyz@google.com>
diff --git a/dashboard/builders.go b/dashboard/builders.go
index 1d92e43..1b95cee 100644
--- a/dashboard/builders.go
+++ b/dashboard/builders.go
@@ -191,27 +191,43 @@
 		ReverseAliases: []string{"solaris-amd64-smartosbuildlet"},
 	},
 	"host-linux-mips": &HostConfig{
-		Notes:          "Run by Brendan Kirby, imgtec.com",
-		IsReverse:      true,
-		env:            []string{"GOROOT_BOOTSTRAP=/usr/local/go-bootstrap-mips"},
+		Notes:     "Run by Brendan Kirby, imgtec.com",
+		IsReverse: true,
+		env: []string{
+			"GOROOT_BOOTSTRAP=/usr/local/go-bootstrap-mips",
+			"GOARCH=mips",
+			"GOHOSTARCH=mips",
+		},
 		ReverseAliases: []string{"linux-mips"},
 	},
 	"host-linux-mipsle": &HostConfig{
-		Notes:          "Run by Brendan Kirby, imgtec.com",
-		IsReverse:      true,
-		env:            []string{"GOROOT_BOOTSTRAP=/usr/local/go-bootstrap-mipsle"},
+		Notes:     "Run by Brendan Kirby, imgtec.com",
+		IsReverse: true,
+		env: []string{
+			"GOROOT_BOOTSTRAP=/usr/local/go-bootstrap-mipsle",
+			"GOARCH=mipsle",
+			"GOHOSTARCH=mipsle",
+		},
 		ReverseAliases: []string{"linux-mipsle"},
 	},
 	"host-linux-mips64": &HostConfig{
-		Notes:          "Run by Brendan Kirby, imgtec.com",
-		IsReverse:      true,
-		env:            []string{"GOROOT_BOOTSTRAP=/usr/local/go-bootstrap-mips64"},
+		Notes:     "Run by Brendan Kirby, imgtec.com",
+		IsReverse: true,
+		env: []string{
+			"GOROOT_BOOTSTRAP=/usr/local/go-bootstrap-mips64",
+			"GOARCH=mips64",
+			"GOHOSTARCH=mips64",
+		},
 		ReverseAliases: []string{"linux-mips64"},
 	},
 	"host-linux-mips64le": &HostConfig{
-		Notes:          "Run by Brendan Kirby, imgtec.com",
-		IsReverse:      true,
-		env:            []string{"GOROOT_BOOTSTRAP=/usr/local/go-bootstrap-mips64le"},
+		Notes:     "Run by Brendan Kirby, imgtec.com",
+		IsReverse: true,
+		env: []string{
+			"GOROOT_BOOTSTRAP=/usr/local/go-bootstrap-mips64le",
+			"GOARCH=mips64le",
+			"GOHOSTARCH=mips64le",
+		},
 		ReverseAliases: []string{"linux-mips64le"},
 	},
 }