* Teach ztrftime() %9. and %N for nanoseconds
* Update prompt expansion to pass sub-second times for time formatting
* Update zsh/stat to pass sub-second times for atime/mtime/ctime
Patch heavily based on Oliver's earlier work @ workers/24059
fixes
Src/utils.c: properly ifdef declarations
Src/zsh_system.h: memmove() should return its dest argument
Src/signals.c: define ret before use
Src/mem.c: remove unused pointers
Src/prototypes.h: use size_t in bcopy()
Src/compat.c: fix const declaration inconsistency