This adds patches proposed upstream to enable downgrades across
major glibc versions.
File list construction and the find-debuginfo.sh wrapper had
to be adjusted to cope with the changed file name patterns.
This needs a wrapper script around find-debuginfo.sh, so that
ld.so is not stripped.
This commit resolves debuginfo file conflicts (#1886295) because
the ldconfig debuginfo file now includes the architecture name.
All debugging information is preserved in ld.so (#1905611). With
the distribution defaults, we strip all binaries again (#1661510).