All check 64 bit based on 64 appearing in @@version_compile_machine. On s390x this isn't the case.
version_compile_machine is derived from SYSTEM_TYPE which though a lot of hackery in cmake/package_name.cmake defines PLATFORM. In s390x's case this is based on CMAKE_SYSTEM_PROCESSOR which in the unix case is from uname -m. On s390x this is exactly "s390x" hence no-match and therefore 32 bit (which is definitely not the case).
As most of the mtr tests that use this macro are using it because of the UINT_MAX value used in system variable, lets use that as the test case for 32 vs 64 bit.