[FYI] {maint} distcheck: never make part of $(distdir) world-writable

This fixes a locally-exploitable security vulnerability (CVE-2012-3386). In the 'distcheck' rule, we used to make the just-extracted (from the distribution tarball) $(distdir) directory and all its files and subdirectories read-only; then, in order to create the '_inst' and '_build'

Re: [FYI] {maint} distcheck: never make part of $(distdir) world-writable

Stefano Lattarini wrote: This fixes a locally-exploitable security vulnerability (CVE-2012-3386). In the 'distcheck' rule, we used to make the just-extracted (from the distribution tarball) $(distdir) directory and all its files and subdirectories read-only; then, in order to create the