.zdebug is unlikely used any longer: gcc -gz switched from legacy
.zdebug to SHF_COMPRESSED with binutils 2.26 (2016), which has been
several years. clang 14 dropped -gz=zlib-gnu support. According to
Debian Code Search (gz=zlib-gnu), no project uses -gz=zlib-gnu.
Remove .zdebug support to (a) simplify code and (b) allow removal of llvm-mc's