Make :outdated work with --nolegacy_external_runfiles

[fmeum]

With --nolegacy_external_runfiles, the working directory relative path
to outdated.jar should start with ../ rather than external/.

Fixes #538.

[cheister]

Thanks for the fix. Mind adding the following test in this PR as well?

diff --git a/tests/bazel_run_tests.sh b/tests/bazel_run_tests.sh
index a1ad9d9..b5af874 100755
--- a/tests/bazel_run_tests.sh
+++ b/tests/bazel_run_tests.sh
@@ -20,7 +20,14 @@ function test_outdated() {
   expect_log "junit:junit \[4.12"
 }
 
-TESTS=("test_duplicate_version_warning" "test_outdated")
+function test_outdated_no_external_runfiles() {
+  bazel run @regression_testing//:outdated --nolegacy_external_runfiles >> "$TEST_LOG" 2>&1
+
+  expect_log "Checking for updates of .* artifacts against the following repositories"
+  expect_log "junit:junit \[4.12"
+}
+
+TESTS=("test_duplicate_version_warning" "test_outdated" "test_outdated_no_external_runfiles")
 
 function run_tests() {
   printf "Running bazel run tests:\n"

[fmeum]

Thanks for the suggestion, done. Not sure about the test failures:

Analysis of target '//:my_app' failed; build aborted: Bazel requires Android build tools version 30.0.0 or newer, 28.0.2 was provided

[fmeum]

The CI failures were resolved by merging master. Everything is ready to be merged now.

[jin]

@cheister feel free to merge if it looks good to you!