Currently we have a single manpage which documents all the paths and
varaibles for the native ld-elf.so.1, with a few notes here and there
about where it differs for 32-bit. Whilst the information is there, it's
not as easy to read as it could be. The fact that the manpage is a
(hard) link to the native one also means ld-elf32.so.1 can't be in the
lib32 distribution set like it was before a4330302f22d ("libcompat:
build 32-bit rtld and ldd as part of "everything"") and instead has to
remain in base, as distribute will fail due to not being able to find
the link target in the distribution directory (and it wouldn't be
representable in the tarball either).
Thus, address both these problems at once by making the existing manpage
a template that can be specialised for ld-elf32.so.1(1).