>cc -O -DNLS -DYP -DLIBC_SCCS -DSYSLIBC_SCCS -D_REENTRANT
>-I/usr/src/lib/libc/inc
>lude -D__DBINTERFACE_PRIVATE -DPOSIX_MISTAKE -DFLOATING_POINT  -Werror
>-Wall -Ws
>trict-prototypes -Wmissing-prototypes -Wpointer-arith  -c
>/usr/src/lib/libc/sys/
>mmap.c
>/usr/src/lib/libc/sys/mmap.c:56: conflicting types for `mmap'
>/usr/include/sys/mman.h:88: previous declaration of `mmap'
>*** Error code 1
>
>Stop.

I saw the exact same thing this afternoon.  I had done a sup this
morning about 11am. I'd done a make includes DESTDIR=xxx and a make
builde DESTDIR=xxx and saw what you describe. 

I'm not sure what went wong, but the version of mman.h installed into
the build tree was out-of-date wrt the CVS tree. I copied the newer
mman.h into /sys/sys/ and everything worked fine thereafter.