Fix strict ordering in SymbolMap::Populate

C++ Compare operators need to follow a strict weak ordering
requirement. The implementation used in SymbolMap::Populate didn't
meet this requirement.

Bug: 893369
Change-Id: Id1b7e4e7c46feb3bf2098ff810656d1d003aef8c
Tested: Flakiness is gone.
Reviewed-on: https://chromium-review.googlesource.com/c/1286763
Commit-Queue: Fabrice de Gans-Riberi <fdegans@chromium.org>
Commit-Queue: Wez <wez@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600551}

base/debug/stack_trace_fuchsia.cc

@@ -149,7 +149,7 @@ void SymbolMap::Populate() {
 
   std::sort(
       &entries_[0], &entries_[count_ - 1],
-      [](const Entry& a, const Entry& b) -> bool { return a.addr >= b.addr; });
+      [](const Entry& a, const Entry& b) -> bool { return a.addr > b.addr; });
 
   valid_ = true;
 }