[racket-dev] configure not finding system installed libffi

Hello,
On OpenBSD I have these files installed:

/usr/local/include/ffi.h
/usr/local/include/ffitarget.h
/usr/local/lib/libffi.a
/usr/local/lib/libffi.la

When I run ./configure, it is not finding libffi and compiles the 
bundled libffi instead.

Running this line gives "configure: error: C compiler cannot create 
executables":

env LDFLAGS="-L/usr/local/lib" CPPFLAGS="-I/usr/local/bin/include" 
LIBS="-lffi" ./configure

Without LIBS="-lffi" it is compiling, but with bundled libffi.

Am I doing something wrong?

Regards,
Lasse