androidtest.bash: drop noisy adb sync output

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/138070043
go/parser: initialize file set even in only some tests are run

Without this fix, some tests crashed (e.g. go test -run Invalid).

LGTM=adonovan
R=adonovan
CC=golang-codereviews
https://codereview.appspot.com/133580043