Boost is not properly detected on macos

[mminutoli]

The root cause is that ck is looking for a dynamic library with a .so extension while it should be .dylib

[gfursin]

Ehh, yes, that's right. I didn't use CK on Mac myself, so some of my colleagues fixed such issues for Mac, but not all. I will try to provide a better support for .dylib shortly ... Will tell you when ready.

[gfursin]

I added a support to use the following CK internal names instead of .so, .dylib, .exe in the "soft_file"

    "soft_file": {
      "linux": "libboost_system$#file_ext_dll#$", 
      "win": "libboost_system*-mt*$#file_ext_lib#$"
    }, 

These extensions will be substituted from the target OS. I updated boost soft meta so normally it shoud search for .dylib on MacOS now. (@dsavenko since you use MacOS, do you mind to help check it, please?)
Don't forget to update ck-env repo:

$ ck pull repo:ck-env

These issues may occasionally appear in some other soft descriptions - in such case, their meta should be also update using above file extensions.

Hope it will work! Thanks!