ANSIfy include/linux/a.out.h and include/linux/nls.h

Hello all :))

The GCC compiler insists on ANSIfying the two files mentioned in
the subject, and I think that it should be done by the kernel maintainers, not GCC ones.

The little patch for 'nls.h' is to add conditional preprocessor
constructs around a typedef:

    typedef __u16 wchar_t;

    typedef __u16 wchar_t;

The patch for 'a.out.h' is smaller, though:

|#ifdef linux

|#ifdef __linux__

Well, I cannot really see why the ANSI standard is violated in
those two files, but if it is, the changes are pretty small to do...

Raúl