binary-io: Define set_binary_mode function.

binary-io: Define set_binary_mode function.

* lib/binary-io.h (set_binary_mode): New function.
(SET_BINARY): Define in terms of set_binary_mode.
* modules/binary-io (configure.ac): Require AC_C_INLINE.
* tests/test-binary-io.c (main): Accept an argument, and test either
set_binary_mode or SET_BINARY depending on the argument.
* tests/test-binary-io.sh: Invoke test-binary-io twice, with an
argument. Clean up also t-bin-out0.tmp.