It now uses $XDG_CONFIG_HOME/isyncrc. A more customary location would be $XDG_CONFIG_HOME/isync/config rather than$XDG_CONFIG_HOME/isyncrc or $XDG_CONFIG_HOME/isync/mbsyncrc. Having a separate directory is especially a good idea since for some reason, relative paths are interpreted from the directory containing the config file rather than ${MAILDIR-${HOME}/Mail} (I've been working on an MR to change the base path for relative paths, but I'm sure it'll get rejected even if I get it working correctly...
Update spec file
My submitted patch still uses ~/.abook if it's present as not to break existing installations but uses $XDG_DATA_HOME/abook for new installations. Here's to hoping it'll land in 0.6.2, if there's ever such a thing (with all the improvements made since 0.6.1, there should be).
XDG directory support
I've noticed that too (I created a symlink to the OpenSSL 1.0 compat library, in a directory pointed to by -Fl in my compiler config file, but I don't know how much longer the distro I use will provide it) and have wondered if it's worth trying to track down the problem and submit a patch. This project doesn't seem particularly active, so I'm doubtful it would be applied.
Doesn't compile in modern compilers
Odd. The sed calls in the Makefile should take care of the case conversions.
Fixed compiling on Linux