Log Message:
Update to stunnel-5.70.

Fix the configure sysconfdir path to point to PKG_SYSCONFBASE instead of
PKG_SYSCONFDIR, as stunnel already appends 'stunnel' path component to
its sysconfdir resolution.

Issue investigated and reported to me by spz@, thanks!

Changelog:

Version 5.70, 2023.07.12, urgency: HIGH

    Security bugfixes
        OpenSSL DLLs updated to version 3.0.9.
        OpenSSL FIPS Provider updated to version 3.0.8.
    Bugfixes
        Fixed TLS socket EOF handling with OpenSSL 3.x. This bug caused major \ 
interoperability issues between stunnel built with OpenSSL 3.x and Microsoft's \ 
Schannel Security Support Provider (SSP).
        Fixed reading certificate chains from PKCS#12 files.
    Features
        Added configurable delay for the "retry" option.