[plt-scheme] extensions that use libraries with libc (cygwin)

Hi,

I'm trying to compile an extension with mzc under cygwin that requires an
external library and haven't had much luck. The external library itself
requires the libc library, so it's giving lots of errors about undefined
symbols such as __assert, atoi, sprintf, etc. But the following didn't
help:

    mzc --cc myext.c
    mzc ++ldl 'C:\cygwin\lib\libc.a' ++ldl 'C:\libfoo.a' -e myext.obj

I still get the same errors (visible with the --ldl-show option) that it
can't resolve all those standard libc symbols that are referenced in
libfoo.a. Any ideas what I'm doing wrong?

Also, is there any danger in using external libraries that use
malloc/free? That is, in the above example, libfoo.a is a library that
uses malloc and free, but myext.c does not.

Thanks,
Dave