ARROW-5325: [Archery][Benchmark] Output properly formatted jsonlines from benchmark diff cli command

Author: Krisztián Szűcs <szucs.krisztian@gmail.com>

Closes #4274 from kszucs/hook-test and squashes the following commits:

2be8098 <Krisztián Szűcs> remove arm intrinsics headers
3c8deb1 <Krisztián Szűcs> __ARM_NEON__ is legacy
20e4850 <Krisztián Szűcs> clang-format
55d2c77 <Krisztián Szűcs> intrinsics
29bded6 <Krisztián Szűcs> clang format
f1f4f92 <Krisztián Szűcs> remove intrinsics include
35f6468 <Krisztián Szűcs> arm intrinsics
de8389d <Krisztián Szűcs> write line separator to output properly formatted jsonlines

Author: kszucs

cpp/src/arrow/compute/kernels/aggregate-benchmark.cc

@@ -18,22 +18,16 @@
 #include "benchmark/benchmark.h"
 
 #include <vector>
-#ifdef _MSC_VER
-#include <intrin.h>
-#else
-#include <immintrin.h>
-#endif
 
 #include "arrow/builder.h"
-#include "arrow/memory_pool.h"
-#include "arrow/testing/gtest_util.h"
-#include "arrow/testing/random.h"
-#include "arrow/util/bit-util.h"
-
 #include "arrow/compute/benchmark-util.h"
 #include "arrow/compute/context.h"
 #include "arrow/compute/kernel.h"
 #include "arrow/compute/kernels/sum.h"
+#include "arrow/memory_pool.h"
+#include "arrow/testing/gtest_util.h"
+#include "arrow/testing/random.h"
+#include "arrow/util/bit-util.h"
 
 namespace arrow {
 namespace compute {

dev/archery/archery/cli.py

@@ -352,9 +352,12 @@ def benchmark_diff(ctx, src, preserve, suite_filter, benchmark_filter,
 
         regressions = 0
         runner_comp = RunnerComparator(runner_cont, runner_base, threshold)
+
+        # TODO(kszucs): test that the output is properly formatted jsonlines
         for comparator in runner_comp.comparisons:
             regressions += comparator.regression
             json.dump(comparator, output, cls=JsonEncoder)
+            output.write('\n')
 
         sys.exit(regressions)