Add x86_64 unwinding problems to Known Issues. am: 371d8955a1 am: 5929e0bcbf am: 611c2ff1fe am: 41d0a91bd7
Add x86_64 unwinding problems to Known Issues. am: 371d8955a1 am: 5929e0bcbf am: 611c2ff1fe am: 41d0a91bd7

Original change: https://android-review.googlesource.com/c/platform/external/perfetto/+/1642140

Change-Id: I72162c1b3382a8b8d0efba756625daaf70cc2ba5

google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto