[polly] polly: Fix files that contain Python 3 SyntaxErrors (PR #124424)

[Christian Clauss via llvm-commits]

cclauss wrote:

I modified the title as requested.

https://repo.or.cz/isl.git/history/HEAD:/imath returns a 500 error and poking around in 
https://repo.or.cz/isl.git I am unable to find imath.  I probably misunderstand this site.

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This pull request was not attempting to complete the port to Python 3.  As recommended in the following locations, the pull request was only focused on stage-1 changes:
* https://portingguide.readthedocs.io/en/latest/process.html#port-the-code
* https://python-future.org/automatic_conversion.html#stage-1-safe-fixes

Proving that Python 2 tests still run successfully without Python 3 syntax errors is a gate before porting to Python 3.  The upstream imath has already made stage 2 modifications by removing .iteritems() and .xrange() which changes Python 2 behavior.

https://github.com/llvm/llvm-project/pull/124424