devtools/v23/profiles: Support android target of syncbase profile.
devtools/v23/profiles: Support android target of syncbase profile.

This CL enables one to build the syncbase dependencies for android with
the following command:

    GOOS=android GOARCH=arm v23 profile install syncbase

The built libraries are installed in $V23_ROOT/third_party/cout/android_arm.

The normal syncbase profile still works and can be installed with "v23
profile install syncbase" as usual.

Change-Id: Icbf24177c17b4bc5ea8d0eb86c4f98cfdd8a33c6

vanadium/go.jiri,vanadium/go.jiri