[libclc] Create LIBCLC_OUTPUT_LIBRARY_DIR directory before build

[wenju-he]

This fixes No such file or directory error when "Unix Makefiles" generator is used, see intel/llvm#20058.

Ninja generator implicitly creates output directory when generating libclc libraries, but "Unix Makefiles" generator does not.

[Copilot]

Pull Request Overview

This PR fixes a build error in libclc when using the "Unix Makefiles" generator by ensuring the output directory exists before attempting to build libraries.

• Adds explicit directory creation for LIBCLC_OUTPUT_LIBRARY_DIR using CMake's file(MAKE_DIRECTORY) command
• Addresses inconsistency between Ninja and Unix Makefiles generators where Ninja implicitly creates directories but Unix Makefiles does not

[arsenm]

Seems like a cmake bug

[wenju-he]

Seems like a cmake bug

Thanks for the review.
AI search show this is expected behavior "Unix Makefiles" generator.

The Ninja generator takes a more explicit and proactive approach to ensuring output directories exist, aligning with its focus on robust and efficient parallel builds. The "Unix Makefiles" generator, in contrast, relies more on the implicit directory creation capabilities of the underlying make commands and the build environment.