ruby-readline fails to build on OS X (Yosemite)

[Louis Guillaume <louis%zabrico.com@localhost>]

Hi,

I'm having problems building devel/ruby-readline on Darwin. Here's the 
error:

...
checking for rl_delete_text() in 
stdio.h,readline/readline.h,readline/history.h... yes
checking for rl_hook_func_t* in 
stdio.h,readline/readline.h,readline/history.h... yes
creating Makefile
===> Building for ruby215-readline-2.1.5nb1
compiling readline.c
linking shared-object readline.bundle
bmake: exec() failed (No such file or directory)
*** Error code 1

Nothing related to readline in /etc/mk.conf.

Not sure where to even start. The "mkmf.log" in the build directory 
doesn't seem very helpful. Any guidance would be great. Thanks,

It builds fine on i386 and amd64.

Louis