math/cln: fix build on powerpc64 elfv2, simplify port

powerpc64 elfv2 needs the same patches as arm* and aarch64, but builds without -DNO_ASM. Simplify the port by applying the arm patches everywhere and use CPPFLAGS_${ARCH} instead of .if ${ARCH} block. Build passes on powerpc64 elfv1 fine, so the original issue must have been fixed.

PR: 242296
Approved by: wen (maintainer), linimon (mentor)