Compilation on mac

[friguzzi]

On a mac with os Mojave, swipl 8.1.3-26-g30498cd0a

doesn't compile, I get

% /Users/rzf/lib/swipl/bin/x86_64-darwin/swipl-ld -Wall -shared -O2 -gdwarf-2 -g3 -o lib/x86_64-darwin/ffi4pl.so c/ffi4pl.c -lffi
ERROR: In file included from c/ffi4pl.c:40:
ERROR: /Users/rzf/lib/swipl/include/SWI-Stream.h:58:10: fatal error: 'wchar.h' file not found
ERROR: #include <wchar.h>
ERROR:          ^~~~~~~~~
% 1 error generated.
% /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/cc returned code 256
% *** /Users/rzf/lib/swipl/bin/x86_64-darwin/swipl-ld exit status 1
% make: *** [lib/x86_64-darwin/ffi4pl.so] Error 1
ERROR: Process "process(path(make),[all])": exit status: 2
ERROR: In:
ERROR:   [14] throw(error(process_error(...,...),_14266))
ERROR:   [12] '$apply':forall(prolog_pack:member(all,...),prolog_pack:run_process(...,...,...)) at /Users/rzf/lib/swipl/boot/apply.pl:51
ERROR:    [7] <user>
ERROR: 
ERROR: Note: some frames are missing due to last-call optimization.
ERROR: Re-run your program in debug mode (:- debug.) to get more 
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