Fix definition from ENABLE_NO_UNDERSCORE_API CMake config option

[imciner2]

The code guarding the use of underscores uses the define BLIS_ENABLE_NO_UNDERSCORE_API, but the CMake config option was actually defining ENABLE_NO_UNDERSCORE_API, so the config option was never propagating into the code. This updates the CMake build system to define the correct thing.

[chandrkr]

Hi @imciner2,

Thank you for your interest in contributing to AOCL-BLAS and helping improve the project.
We appreciate the changes you've proposed in this pull request — they are valid and valuable.

However, our CI/CD pipeline has detected a build error on Windows OS related to this PR. We've attached the build log and the steps used during the build process for your reference.

Kindly review the logs and update the same pull request with a new commit to address the issue.
Once again, thank you for your contribution!

build_commands.txt
build_log.txt