[roll] Roll fuchsia [starnix] Introduce tid_t

This allows to better differentiate between thread and process id.

Also fixed ptrace code that was mixing the 2.

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1282244
Original-Revision: 53b9b3b28d443dc109d71a089cb25ae27b8b5937
GitOrigin-RevId: be6d8a617ed688c611a9fb2a572651a4a07024fe
Change-Id: I8e2806e5ffc4b7b015059c588b23714153450d20
diff --git a/stem b/stem
index 63e0431..40dfbac 100644
--- a/stem
+++ b/stem
@@ -7,7 +7,7 @@
             manifest="manifests/platform"
             root=""
             remote="https://fuchsia.googlesource.com/fuchsia"
-            revision="e2552ccf5c2b8eaaf3e396e625c886c2cd5d5d53"/>
+            revision="53b9b3b28d443dc109d71a089cb25ae27b8b5937"/>
   </imports>
   <projects>
     <project name="cobalt"