gdb: rename displaced_step_closure to displaced_step_copy_insn_closure

gdb: rename displaced_step_closure to displaced_step_copy_insn_closure

Since we're going to introduce other "displaced step" functions and
another kind of displaced step closure, make it clear that this is the
return type of the gdbarch_displaced_step_copy_insn function.

gdb/ChangeLog:

	* infrun.h (get_displaced_step_closure_by_addr): Rename to...
	(get_displaced_step_copy_insn_closure_by_addr): ... this.
	Update all users.
	(displaced_step_closure): Rename to...
	(displaced_step_copy_insn_closure): ... this.  Update all users.
	(displaced_step_closure_up): Rename to...
	(displaced_step_copy_insn_closure_up). ... this.  Update all
	users.
	(buf_displaced_step_closure): Rename to...
	(buf_displaced_step_copy_insn_closure): ... this.  Update all
	users.
	* infrun.c (get_displaced_step_closure_by_addr): Rename to...
	(get_displaced_step_copy_insn_closure_by_addr): ... this.
	Update all users.
	* aarch64-tdep.c (aarch64_displaced_step_closure): Rename to...
	(aarch64_displaced_step_copy_insn_closure): ... this.  Update
	all users.
	* amd64-tdep.c (amd64_displaced_step_closure): Rename to...
	(amd64_displaced_step_copy_insn_closure): ... this.  Update all
	users.
	* arm-tdep.h (arm_displaced_step_closure): Rename to...
	(arm_displaced_step_copy_insn_closure): ... this.  Update all
	users.
	* i386-tdep.h (i386_displaced_step_closure): Rename to...
	(i386_displaced_step_copy_insn_closure): ... this.  Update all
	users.
	* rs6000-tdep.c (ppc_displaced_step_closure): Rename to...
	(ppc_displaced_step_copy_insn_closure): ... this.  Update all
	users.
	* s390-tdep.c (s390_displaced_step_closure): Rename to...
	(s390_displaced_step_copy_insn_closure): ... this.  Update all
	users.
	* gdbarch.h: Re-generate.
	* gdbarch.c: Re-generate.

Change-Id: I11f56dbcd4c3532fb195a08ba93bccf1d12a03c8