On platforms where closefrom returns void (eg glibc>=2.34) the prototype
for closefrom in its compat tests would cause compile errors. Remove
this and have the tests pull in the compat headers in the same way as
the main code. bz#3336.
openbsd-compat/regress/{.cvsignore,Makefile.in,opensslvertest.c}]
Move the OpenSSL header/library version test into its own function and add
tests for it. Fix it to allow fix version upgrades (but not downgrades).
Prompted by chl@ via OpenSMTPD (issue #462) and Debian (bug #748150).
ok djm@ chl@