[scudo][standalone] Remove the pthread key from the shared TSD am: 2b968afdaa am: f76b22141c am: 67448c6d00 am: 5badf9a1ff

Original change: https://android-review.googlesource.com/c/platform/external/scudo/+/1434532

Change-Id: Ia31ce14d9b767c7c2cfb80b1d9e2202f5cdaba93