Bug#788883: perl: drop (most of) debian/prefix_changes.diff

[Niko Tyni]

Package: perl
Version: 5.22.0-1
Severity: wishlist

I think it's high time we dropped the EU:MM changes that still allow
 make install PREFIX=something
to work with Makefile.PL based packages. Upstream has recommended DESTDIR
instead since 2002, see #568748 and #545904.

There's been a somewhat heuristic lintian check for five years visible at
 https://lintian.debian.org/tags/debian-rules-makemaker-prefix-is-deprecated.html
and it's currently down to 55 packages. The logic in the check is basically
  tag if ($uses_makefile_pl && /install.*PREFIX/ && !/DESTDIR/)

It looks like debian/prefix_changes.diff contains some unrelated
changes, at least 

-       \$(NOECHO) \$(POD2MAN) --section=$section --perm_rw=\$(PERM_RW)
+       \$(NOECHO) \$(POD2MAN) --section=\$(MAN${section}EXT) --perm_rw=\$(PERM_RW)

that should be broken out in any case.

I expect affected packages will start to FTBFS, as seen in #545904,
so a full check would be "just" a simple matter of building the archive
with and without the patch, comparing the results and filing bugs :)
This could just as well be tested with the 5.20 packages in sid.

Alternatively, if a full check seems overkill, we could just check the 55
packages noticed by lintian and let the rest be fixed in their own time
when they start to fail.

Thoughts?
-- 
Niko Tyni   ntyni at debian.org