bug#55449: recutils cross-compilation "fix" breaks bash builtins

[Liliana Marie Prikler]

Hi Guix,

The fix in commit 20fbd870938e239c038d8524a56729f123f19f80, which lets
recutils cross-compile unfortunately omits support for the bash
builtins in all build modes, as recutils can't actually detect bash
headers there.

Unfortunately, recutils' configure.ac silently swallows this error in
the following check.
  AM_CONDITIONAL([BASH_BUILTINS],
                 [test "x$bash_headers_available" = "xyes" && 
                  test "x$bash_builtins_enabled" = "xyes"])
I only noticed, because I symlink the builtins to lib/bash, where
they're actually needed, which causes runpath validation to fail
because the symlink points to a file that doesn't exist.  I fixed this
locally, but still wanted y'all to know.

Is there a way we can support bash headers in cross-compilation
contexts?  I don't think having bash:include as a native input is even
helpful here, is it?  WDYT?