[Mono-osx] Cannot build mono-4.2.0-branch on el capitan

[Saulius Menkevičius]

Hi,

Recently I've been trying to build 4.2, then 4.0 and 3.12 versions of
mono on my mac with OS X 10.11 (El Capitan) and I always get stuck on this
error:

    CCLD     libmonogc.la
    libtool: warning: '-version-info/-version-number' is ignored for convenience libraries
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ar: illegal option -- .
    usage:  ar -d [-TLsv] archive file ...
            ar -m [-TLsv] archive file ...
            ar -m [-abiTLsv] position archive file ...
            ar -p [-TLsv] archive [file ...]
            ar -q [-cTLsv] archive file ...
            ar -r [-cuTLsv] archive file ...
            ar -r [-abciuTLsv] position archive file ...
            ar -t [-TLsv] archive [file ...]
            ar -x [-ouTLsv] archive [file ...]
    make[4]: *** [libmonogc-static.la] Error 1

I used to be able to do builds of 3.12 on OS X 10.10 and it worked
ok. Should I update my toolset in some special way? Currently I have the
standard Xcode 7.1 command line tools installed.

Thank you,

-- 
Saulius Menkevičius (saulius.menkevicius at gmail.com)