Limit SelectAllEvents benchmark to 512 FDs

...since `select` only supports FD values up to 1024 and creating 1024
event FDs will result in FD values that are greater than 1024 because
of the initial set of FDs that exist for most programs (stdin, stdout,
stderr).

https://www.man7.org/linux/man-pages/man2/select.2.html

PiperOrigin-RevId: 573916775

test/perf/linux/select_benchmark.cc

@@ -46,6 +46,8 @@ void Setup(int count, std::vector<FileDescriptor>& event_fds, fd_set& read_fds,
     FD_SET(fd.get(), &read_fds);
     event_fds.push_back(std::move(fd));
   }
+
+  ASSERT_LT(max_fd, FD_SETSIZE);
 }
 
 // Benchmarks a call to select(2) when no FD is "ready" with varying timeout
@@ -94,7 +96,7 @@ void BM_SelectAllEvents(benchmark::State& state) {
   }
 }
 
-BENCHMARK(BM_SelectAllEvents)->Range(/*start=*/2, /*limit=*/1024);
+BENCHMARK(BM_SelectAllEvents)->Range(/*start=*/2, /*limit=*/512);
 
 }  // namespace