commit 66b00755736eaf7686b954f8e0deae970a78b7e7
author Sim Sun <simsun@fb.com> Thu Apr 16 04:02:59 2020 -0700
committer Christopher Ferris <cferris@google.com> Fri May 01 17:24:57 2020 -0700
tree 1c323f54cae05070deb499e99c60a6652b65bbd7
parent d1f7636e522897a60b29e9f4a1a1119e1da35d0d

Fix dangling pointer issue in LocalUpdatbleMaps

Libunwindstack would remove duplicated items and update the `prev_map`
during reparsing `/proc/self/maps`. But we leave `prev_real_map`
pointing toward a MapInfo that will be deleted soon. It will cause a
dangling pointer issue.

Add new tests to cover this dangling pointer issue.

Bug: 155511785

Test: libunwindstack_test
Change-Id: I62e1b97bcb73f07e9349671f0b758f5ec9de16c0
(cherry picked from commit a7a194beb4a28f2da3d5098d1258d7284cca2b13)