x/build: android subrepo builds need to sync data files

[mikioh]

See http://build.golang.org/log/ec8be097b936c5cf78f7d984ae62d39451ba6dff

go_android_exec: adb shell mkdir -p /data/local/tmp/charset.test-1846
go_android_exec: adb push /tmp/go-build720098852/golang.org/x/net/html/charset/_test/charset.test /data/local/tmp/charset.test-1846/charset.test-1846-tmp
1465 KB/s (3495200 bytes in 2.329s)
go_android_exec: adb shell cp '/data/local/tmp/charset.test-1846/charset.test-1846-tmp' '/data/local/tmp/charset.test-1846/charset.test-1846'
go_android_exec: adb shell rm '/data/local/tmp/charset.test-1846/charset.test-1846-tmp'
go_android_exec: adb shell export TMPDIR="/data/local/tmp/charset.test-1846"; export GOROOT="/data/local/tmp/goroot"; export GOPATH="/data/local/tmp/gopath"; cd "/data/local/tmp/gopath/src/golang.org/x/net/html/charset"; '/data/local/tmp/charset.test-1846/charset.test-1846' -test.short=true; echo -n exitcode=$?
/system/bin/sh: cd: /data/local/tmp/gopath/src/golang.org/x/net/html/charset: No such file or directory

[rsc]

@crawshaw but pretty sure this is working as intended.

[crawshaw]

go_android_exec is working as intended. But this could work, with some android-specific handling is needed in the sub-repository builder. In particular, the logic from go/src/androidtest.bash needs to be replicated.