Add target_xfer_partial_ftype

Add target_xfer_partial_ftype

This patch adds a typedef target_xfer_partial_ftype.  When we change
the signature of xfer_partial functions (for example, adding a new
parameter), we don't have to modify all of their declarations.

This patch also updates the type of parameters of target_xfer_partial
from "void *" to "gdb_byte *".

gdb:

2013-12-18  Yao Qi  <yao@codesourcery.com>

	* target.h (target_xfer_partial_ftype): New typedef.
	(target_xfer_partial): Update declaration.
	* auxv.h (memory_xfer_auxv): Likewise.
	* ia64-hpux-nat.c (super_xfer_partial): Likewise.
	* ia64-linux-nat.c (super_xfer_partial): Likewise.
	* linux-nat.c (super_xfer_partial): Likewise.
	* procfs.c (procfs_xfer_partial): Likewise.
	* record-full.c (record_full_beneath_to_xfer_partial):
	(tmp_to_xfer_partial): Likewise.
	* sparc-nat.c (inf_ptrace_xfer_partial): Likewise.
	* target.c (default_xfer_partial): Likewise.
	(current_xfer_partial): Likewise.
	(target_xfer_partial): Change parameter type to 'gdb_byte *'.