correct how terminating L'\0' is added;
change return to match standard for when output does not fit;
some corrections and enhancements to the docs.
* libc/stdio/vswprintf.c (_vswprintf_r): ditto, except for docs.
* libc/stdio/vfwprintf.c: some corrections to the docs and some
enhancements to comments. (No code changes.)
* libc/time/strftime.c: Correct some problems that made wcsftime()
not work correctly: work properly with swprintf returns that are
different from snprintf returns, correct test vector lengths for
when sizeof(wchar_t) > 1.
* libc/stdio/sprintf.c: Some documentation and comment corrections and
enhancements to match those done to swprintf.c.
4a825d4145