On Android libraries there are zero length entries within the ranged
symbols which break our range processing. This updates the logic to
only add entries for zero-length entries if they aren't within the range
of the previously added entry.

Change-Id: I511a6221817c535d967a50413948a29d9deb1e85
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1627985
Auto-Submit: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61903}