Please backport 62c352e13c14 to release/18.x

[zahiraam]

In #76873 a warning was added when the macros INFINITY and NAN are used in binary expressions. But that generated some redundant warnings. #80290 fixes that.

/cherry-pick 62c352e

[llvmbot]

/pull-request #80845

[llvmbot]

@llvm/issue-subscribers-flang-frontend

Author: Zahira Ammarguellat (zahiraam)

In https://github.com//pull/76873 a warning was added when the macros INFINITY and NAN are used in binary expressions. But that generated some redundant warnings. https://github.com//pull/80290 fixes that.

/cherry-pick 62c352e