androidtest.bash: drop noisy adb sync output

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/138070043

src/androidtest.bash

@@ -47,7 +47,9 @@ ln -s $GOROOT/src/cmd $FAKE_GOROOT/src/cmd
 ln -s $GOROOT/src/pkg $FAKE_GOROOT/src/pkg
 ln -s $GOROOT/test $FAKE_GOROOT/test
 ln -s $GOROOT/lib $FAKE_GOROOT/lib
-adb sync data
+echo '# Syncing test files to android device'
+time adb sync data &> /dev/null
+echo ''
 rm -rf "$ANDROID_PRODUCT_OUT"
 
 # Run standard build and tests.