constify path_get/path_put and fs_struct.c stuff

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --cc fs/fs_struct.c
Simple merge

diff --cc fs/internal.h
Simple merge

diff --cc fs/namei.c
Simple merge

diff --cc include/linux/fs_struct.h
Simple merge

diff --cc include/linux/path.h
Simple merge