* configure.in: Add new --enable-newlib-reent-small option.
* configure: Regenerated.
* acconfig.h: Add _WANT_REENT_SMALL.
* newlib.hin: Regenerated minus PACKAGE macros to add
_WANT_REENT_SMALL macro.
* libc/include/sys/config.h[_WANT_REENT_SMALL]: Set _REENT_SMALL
if not already set.
* libc/stdio/fflush.c[_REENT_SMALL]: Return immediately if
there is no buffer.
* libc/stdio/local.h[_REENT_SMALL]: Fix CHECK_INIT macro to
use reentrant pointer passed in when resetting the file
pointer to one of the std streams.