Don't copy LinuxPerf Stats

It's not clear to me how deep the copying should be, but I think this should be fine for now and it matches the semantics of `copy` better.

Author: Zentrik

src/trials.jl

@@ -30,7 +30,7 @@ function Base.copy(t::Trial)
         copy(t.gctimes),
         t.memory,
         t.allocs,
-        isnothing(t.linux_perf_stats) ? nothing : copy(t.linux_perf_stats),
+        t.linux_perf_stats,
     )
 end
 
@@ -137,7 +137,7 @@ function Base.copy(t::TrialEstimate)
         t.gctime,
         t.memory,
         t.allocs,
-        isnothing(t.linux_perf_stats) ? nothing : copy(t.linux_perf_stats),
+        t.linux_perf_stats,
     )
 end