wrapper: correctly Join() paths for Android

filepath.Join(".", "foo") folds to "foo", which is fine as long as we're
not Exec()ing the result of that Join(). If we do, we might execute a
binary we weren't expecting to (e.g., one looked up from ${PATH}, rather
than the one at ${CWD}).

BUG=None
TEST=`go test`

Change-Id: Ifbd247c2e489c786d0a0d3342b5d1b61a7320796
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/2088432
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Tested-by: George Burgess <gbiv@chromium.org>
3 files changed