[SanitizerCoverage] Use zeroext for cmp parameters on all targets

Commit 9385aaa8 ("[sancov] Fix PR33732") added zeroext to
__sanitizer_cov_trace(_const)?_cmp[1248] parameters for x86_64 only,
however, it is useful on other targets, in particular, on SystemZ: it
fixes swap-cmp.test.

Therefore, use it on all targets. This is safe: if target ABI does not
require zero extension for a particular parameter, zeroext is simply
ignored. A similar change has been implemeted as part of commit
3bc439bd ("[MSan] Add instrumentation for SystemZ"), and there were
no problems with it.

Reviewed By: morehouse

Differential Revision: https://reviews.llvm.org/D85689