[PATCH] lib/sort.c: small cleanups

This patch contains the following small cleanups:
- make two needlessly global functions static
- every file should #include the header files containing the prototypes
  of it's global functions

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>