Autoconf 2.71: runstatedir broken by localstatedir not being expanded

[Patrik Novotny]

# Affected version:
 - 2.70
 - 2.71


# Related bug report:
  - https://lists.gnu.org/archive/html/bug-autoconf/2021-03/msg00001.html


# Description:
According to documentation, runstatedir is supposed to be a subdirectory of
the localstatedir.

However, when --localstatedir value is passed to the configure script, it
does not propagate properly to the runstatedir value. The ${localstatedir}
actually expands to an empty string.

For example if localstatedir is set to '/dir/subdir', the expected
runstatedir would be '/dir/subdir/run'.
Instead it expands to '/run'.

A reproducer can be found in the related bug report above.

-- 
Patrik Novotný
Associate Software Engineer
Red Hat
panovotn@redhat.com