Log Message:
guile22: fix SunOS builds on releases that provide accept4()

Curiously, the only thing stopping this from building was the second
accept4() test in the configure script, which doesn't supply the
necessary linker arguments. Elsewhere, the build configuration does
correctly set those same arguments. On current members of the SunOS
family, this meant it would falsely think accept4() wasn't defined
when it really was, which would then lead to a signature mismatch
during compilation.