[Bug libffi/64572] r219477 breaks bootstrap on x86_64 darwin

[howarth at bromo dot med.uc.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64572

--- Comment #22 from howarth at bromo dot med.uc.edu ---
I did a quick and dirty test in the i386/libffi build directory of rebuilding
and rerunning make check as I reverted each source file and header being
compiled on darwin to the pre-r184997 contents. The test suite failures from
comment 8 remained after all the *.c/*.h changes where reverted and only
disappeared when I finally replaced the generated ffi.h header with one from a
build prior to r184997. So I suspect the problem may actually lie in the
include/ffi.h.in changes.