misc/android: adb push --sync testdata
misc/android: adb push --sync testdata

(A stripped down version of) $GOROOT is uploaded to the device
before running standar library tests, including many (all?)
testdata directories.

Use the --sync flag when pushing testdata directories to the device
in case it is already present.

Change-Id: If8104f9d15838c1be3623adcf831a7188303c376
Reviewed-on: https://go-review.googlesource.com/c/164338
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

CAFxX/go,nawawi/go,golang/go,CAFxX/go,josharian/go,nawawi/go,cloudflare/go,golang/go,golang/go,CAFxX/go,cloudflare/go,golang/go,cloudflare/go,cloudflare/go,CAFxX/go,nawawi/go,cloudflare/go,nawawi/go,josharian/go,nawawi/go,CAFxX/go,akutz/go,golang/go,akutz/go,cloudflare/go,golang/go,cloudflare/go,josharian/go,akutz/go,josharian/go,nawawi/go,CAFxX/go,akutz/go,akutz/go,akutz/go,cloudflare/go,akutz/go,josharian/go,akutz/go,josharian/go,golang/go,nawawi/go,golang/go,CAFxX/go,nawawi/go,josharian/go,josharian/go,CAFxX/go