tweak for cffi-grovel::trim-whitespaces?

Hello, This is on - 64-bit Windows - Msys+mingw64 GCC compilation suite - ccl and/or sbcl (latest Windows version) - cffi 0.16.1. I had problems loading cffi-libffi: - CCL did fine - SBCL barfed during the grovel phase:

Paths returned by pkg-config had a control-M appended to the end

I fixed that by adding \#Return to the list of characters trimmed by cffi-grovel::trim-whitespaces. With that addition both SBCL and CCL loaded cffi-libffi. Mirko