coredump: move dump_write() and dump_seek() into a header file

My next patch will replace ELF_CORE_EXTRA_* macros by functions, putting
them into other newly created *.c files.  Then, each files will contain
dump_write(), where each pair of binfmt_*.c and elfcore.c should be the
same.  So, this patch moves them into a header file with dump_seek().
Also, the patch deletes confusing DUMP_WRITE macros in each files.

Signed-off-by: Daisuke HATAYAMA <[email protected]>
Cc: "Luck, Tony" <[email protected]>
Cc: Jeff Dike <[email protected]>
Cc: David Howells <[email protected]>
Cc: Greg Ungerer <[email protected]>
Cc: Roland McGrath <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Alan Cox <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
4 files changed