libc/glibc: workaround for autoconf'ed define of caddr_t

When building canadian cross compiler, I have some trouble with
configure defining caddr_t as a macro, like:
#define caddr_t char *

When combined with the types.h where caddr_t is protected together
with daddr_t, the typedef of caddr_t breaks.

This patch works around it by protecting the caddr_t typedef
specifically.

I am uncertain as to the real cause and solution to this :-(

Signed-off-by: Esben Haabendal <eha@dev.doredevelopment.dk>

 # SPARC specific config options

 config ARCH_sparc

     select ARCH_SUPPORTS_32

     select ARCH_SUPPORTS_64

     select ARCH_DEFAULT_32

     select ARCH_USE_MMU

     select ARCH_SUPPORT_CPU

     select ARCH_SUPPORT_TUNE

     help

       The SUN SPARC architecture, as defined by:

         32 bit: http://www.sparc.org/standards/V8.pdf

         64 bit: http://www.sparc.org/standards/SPARCV9.pdf