benchmarks: remove more boilerplate.

Many of our benchmarks are basically just "call one function with a
fixed argument". We don't need to keep repeating all the boilerplate for
that.

This also ensures we don't forget the benchmark::DoNotOptimize, which --
in addition to being a good idea in general -- specifically solves the
problem with gettid benchmark and provides a more accurate result by
removing the indirection through a function pointer.

Test: ran benchmarks
Change-Id: Id67535243678cd0d48f51cf25141e2040da9af03
diff --git a/benchmarks/stdlib_benchmark.cpp b/benchmarks/stdlib_benchmark.cpp
index 6afe7aa..ec3f6f2 100644
--- a/benchmarks/stdlib_benchmark.cpp
+++ b/benchmarks/stdlib_benchmark.cpp
@@ -216,45 +216,9 @@
 }
 BIONIC_BENCHMARK_WITH_ARG(BM_stdlib_mbrtowc, "0");
 
-void BM_stdlib_atoi(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(atoi(" -123"));
-  }
-}
-BIONIC_BENCHMARK(BM_stdlib_atoi);
-
-void BM_stdlib_atol(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(atol(" -123"));
-  }
-}
-BIONIC_BENCHMARK(BM_stdlib_atol);
-
-void BM_stdlib_strtol(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(strtol(" -123", nullptr, 0));
-  }
-}
-BIONIC_BENCHMARK(BM_stdlib_strtol);
-
-void BM_stdlib_strtoll(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(strtoll(" -123", nullptr, 0));
-  }
-}
-BIONIC_BENCHMARK(BM_stdlib_strtoll);
-
-void BM_stdlib_strtoul(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(strtoul(" -123", nullptr, 0));
-  }
-}
-BIONIC_BENCHMARK(BM_stdlib_strtoul);
-
-void BM_stdlib_strtoull(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(strtoull(" -123", nullptr, 0));
-  }
-}
-BIONIC_BENCHMARK(BM_stdlib_strtoull);
-
+BIONIC_TRIVIAL_BENCHMARK(BM_stdlib_atoi, atoi(" -123"));
+BIONIC_TRIVIAL_BENCHMARK(BM_stdlib_atol, atol(" -123"));
+BIONIC_TRIVIAL_BENCHMARK(BM_stdlib_strtol, strtol(" -123", nullptr, 0));
+BIONIC_TRIVIAL_BENCHMARK(BM_stdlib_strtoll, strtoll(" -123", nullptr, 0));
+BIONIC_TRIVIAL_BENCHMARK(BM_stdlib_strtoul, strtoul(" -123", nullptr, 0));
+BIONIC_TRIVIAL_BENCHMARK(BM_stdlib_strtoull, strtoull(" -123", nullptr, 0));