[SPARK-12640][SQL] Add simple benchmarking utility class and add Parquet scan benchmarks.

[nongli]

[SPARK-12640][SQL] Add simple benchmarking utility class and add Parquet scan benchmarks.

We've run benchmarks ad hoc to measure the scanner performance. We will continue to invest in this
and it makes sense to get these benchmarks into code. This adds a simple benchmarking utility to do
this.

[rxin]

move this into util package?

[SparkQA]

Test build #48738 has finished for PR 10589 at commit 22afd1f.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • class Benchmark(name: String, valuesPerIteration: Long, iters: Int = 5)
  • case class Case(name: String, fn: Int => Unit)
  • case class Result(avgMs: Double, avgRate: Double)

[davies]

@nongli You don't need to repeat the title in the description of the PR (or it get duplicated in commit message).

[davies]

This should be SQL with ParquetReader

[SparkQA]

Test build #48876 has finished for PR 10589 at commit f231e9a.

• This patch passes all tests.
• This patch does not merge cleanly.
• This patch adds the following public classes (experimental):
  • case class Case(name: String, fn: Int => Unit)
  • case class Result(avgMs: Double, avgRate: Double)

[SparkQA]

Test build #2341 has finished for PR 10589 at commit 4f682c5.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • case class Case(name: String, fn: Int => Unit)
  • case class Result(avgMs: Double, avgRate: Double)

[SparkQA]

Test build #48885 has finished for PR 10589 at commit 4f682c5.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • case class Case(name: String, fn: Int => Unit)
  • case class Result(avgMs: Double, avgRate: Double)

[rxin]

I've merged this. Thanks!