[SPARK-12480][follow-up] use a single column vararg for hash

[cloud-fan]

address comments in #10435

This makes the API easier to use if user programmatically generate the call to hash, and they will get analysis exception if the arguments of hash is empty.

[cloud-fan]

cc @rxin

[rxin]

Can you update the error message to say "hash requires at least one argument"?

[rxin]

LGTM

[rxin]

Oh - we need to add a version for python too...

[SparkQA]

Test build #48743 has finished for PR 10588 at commit 9c72e01.

• This patch fails Python style tests.
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• This patch adds no public classes.

[SparkQA]

Test build #48736 has finished for PR 10588 at commit ba303fd.

• This patch passes all tests.
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• This patch adds no public classes.

[SparkQA]

Test build #48741 has finished for PR 10588 at commit b652b45.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #48750 has finished for PR 10588 at commit f3a557b.

• This patch fails PySpark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #48758 has finished for PR 10588 at commit 9e05b1e.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[rxin]

Thanks - I've merged this.