[FLINK-13450][table api] Use StrictMath instead of Math for exp

[wangxiyuan]

What is the purpose of the change

Some math calculation result is different between x86 and aarch64 because of hardware optimizations.

For exmaple, the Math.exp(1)

on X86 is      2.718281828459045
on aarch64 is  2.7182818284590455 

Use StrictMath can keep the result the same.

Brief change log

Add a new exp functino to use StrictMath instead.

Verifying this change

This change is already covered by existing tests, such as testArithmeticFunctions.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (yes / no)
• The serializers: (yes / no / don't know)
• The runtime per-record code paths (performance sensitive): (yes / no / don't know)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: (yes / no / don't know)
• The S3 file system connector: (yes / no / don't know)

Documentation

• Does this pull request introduce a new feature? (yes / no)
• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)

[wangxiyuan]

@StephanEwen, Hi, this is another place that impact flink-table-planner unit test. Please help review. Thank you very much.

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Last check on commit a697824 (Thu Dec 05 08:45:21 UTC 2019)

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[StephanEwen]

Looks good to me, +1
Will merge once the CI builds are green.

[wangxiyuan]

@StephanEwen Thank you :)