Free the tid buffer when thread enumeration yields nothing.

A task directory yielding no numeric entries (the target exiting
mid-enumeration) returned 0 with the freshly allocated array still
handed back through *out, and the caller's failure path returned without
freeing it.

public/client/TracySysTrace.cpp

@@ -457,6 +457,12 @@ static int EnumerateTaskTids( pid_t pid, uint32_t** out )
         tids[count++] = (uint32_t)tid;
     }
     closedir( dir );
+    if( count == 0 )
+    {
+        tracy_free( tids );
+        *out = nullptr;
+        return 0;
+    }
     *out = tids;
     return (int)count;
 }