Skip automatic shlib permission fix for files in CHECK_SHLIBS_SKIP.
ld.so.1 is a manpage of ld in section 1, not a shlib.
prevent wrong automatic permission fix.
Add CHECK_BUILTIN guard.
We can put any files in files/.
loose mandantory DISTNAME.
DISTNAME is optional now.
No need to define fake DISTNAME and empty MASTER_SITES and DISTFILES now.
Just define PKGNAME and use it.