DYNAMIC_ARCH support for ZArch should be added to CMake build system

[svillemot]

ZArch has DYNAMIC_ARCH support, and it is supported by the Makefile build system. However, the CMake build system seems to lack that feature (see cmake/arch.cmake, where the section about DYNAMIC_ARCH lacks any ZArch entry).

[martin-frbg]

OpenBLAS currently lacks CMake support for building ZArch in general, and I'm not aware of anyone requesting it earlier.

[svillemot]

Sorry, I was not aware of that. I let you decide whether to close this bug or not, depending on your workflow.

[martin-frbg]

I'll see if it can be done quickly, but I'm actually not even sure about routine availability of CMake on ZArch (and I only have the OSUOSL Jenkins service for testing). Do you have an actual need for ZArch/CMake build support, or was this just for the sake of completeness ?

[svillemot]

No, I don’t need it. The Debian package still uses the traditional make build system.

I reported this because I was looking for the list of architectures that have DYNAMIC_ARCH support, and the build system was the only documentation I could find.