This patch adds gnulib-longdouble-redirect.patch, which is a subset of
gnulib commit 776af40e09b476a41073131a90022572f448c189.
This patch must be applied to the copy of gnulib which is vendored
within a few packages, when compiling for platforms that use
longdouble-redirection (a glibc-specific feature). Without it,
compile failures mentioning "__LDBL_REDIR1_DECL" will occur.
Currently there are two packages which need this patch to their
vendored gnulib: gettext and gnused. Both projects have merged a
fixed version of gnulib but have not yet made a release with the fix.
We can drop this patch as soon as both of those projects are
version-bumped.
