[infra] Check to see if addr2line exists before symbolization

Change-Id: If0709604d05beb4e41d7e412b39412debab733f6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/611040
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
1 file changed