Error within the FFI test suite on OS X

[paulfryzel]

There seems to be issues when dynamically loading the bindings for higgs on OS X. This can be seen within the FFI test suite:

var higgs = $ir_load_lib("");

... which eventually results in:

runtime.vm.RunError: run-time error: dlopen(, 1): no suitable image found.

Full make test error output: https://gist.github.com/paulfryzel/11023330

(OS X 10.9.2, DMD64 D Compiler v2.065, Higgs@93c675f)

This error stems from differences in libc between OS's (BSD -vs- Linux). On OS X/BSD, dlopen requires null as its first parameter (path) to default to the main program.

auto lib = dlopen(null, RTLD_LAZY | RTLD_LOCAL); // jit/ops.d L#3967