Rebuilt moxie/configure
* libc/include/stdio_ext.h: Rename __fwriteable to __fwritable.
[!__GNUC__]: Declare real functions for the macros, and make
the macros conditional on !__cplusplus.
* libc/stdio/Makefile.am (ELIX_4_SOURCES): Add stdio_ext.c.
(CHEWOUT_FILES): Add stdio_ext.def.
* libc/stdio/Makefile.in: Regenerate.
* libc/stdio/stdio.tex: Include stdio_ext.def.
* libc/stdio/stdio_ext.c: New file.
	* libc/include/stdio.h: Fix type signature of __sfeof and __sferror
	(and thus feof and ferror) for C++.