/usr/local/bin/csc -feature compiling-extension -setup-mode    -s -O2 -d0 -D sendfile -D mmap -D madvise sendfile.scm -j sendfile
sendfile.c: In function 'stub240':
sendfile.c:80: error: 'errno' undeclared (first use in this function)
sendfile.c:80: error: (Each undeclared identifier is reported only once
sendfile.c:80: error: for each function it appears in.)
sendfile.c:80: error: 'EAGAIN' undeclared (first use in this function)