[clang] [Clang][NFC] Extend cmplx range tests for #131129 (PR #131447)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> This is a lot of tests... do we really need every combination of type/operator/flag? I guess it makes sure we don't have gaps, but thousands of lines of tests seems excessive.

It does seem like a lot of testing, but I'd rather we be excessive than take our historical approach of only getting a fraction of test coverage. (FWIW, it would be nice if we could get coverage reports for testing in Clang and maybe even hook it up to precommit CI so that we reject patches which reduce test coverage ratios rather than increase them, but that's not an issue for this PR.)

https://github.com/llvm/llvm-project/pull/131447