Rename dwarf2 to dwarf in "set debug" and maintenance commands.

Rename dwarf2 to dwarf in "set debug" and maintenance commands.

gdb/ChangeLog:

	* NEWS: Add entries for command renamings.
	* dwarf2read.c (dwarf_read_debug): Renamed from dwarf2_read_debug.
	All uses updated.
	(dwarf_die_debug): Renamed from dwarf2_die_debug.  All uses updated.
	(dwarf_max_cache_age): Renamed from dwarf2_max_cache_age.
	All uses updated.
	(show_dwarf_max_cache_age): Renamed from show_dwarf2_max_cache_age.
	All callers updated.  Fix spelling of DWARF in help text.
	(set_dwarf_cmdlist): Renamed from set_dwarf2_cmdlist.
	All uses updated.
	(show_dwarf_cmdlist): Renamed from show_dwarf2_cmdlist.
	All uses updated.
	(set_dwarf_cmd): Renamed from set_dwarf2_cmd.  All callers updated.
	(show_dwarf_cmd): Renamed from show_dwarf2_cmd.  All callers updated.
	(dwarf_always_disassemble): Renamed from dwarf_always_disassemble.
	All uses updated.
	(show_dwarf_always_disassemble): Renamed from
	show_dwarf2_always_disassemble.  All callers updated.
	(_initialize_dwarf2_read): Rename "set/show dwarf2" prefix to
	"set/show dwarf".  Rename "set/show dwarf2 max-cache-age" to
	"set/show dwarf max-cache-age".  Rename
	"set/show dwarf2 always-disassemble" to
	"set/show dwarf always-disassemble".  Rename
	"set/show debug dwarf2-read" to "set/show debug dwarf-read".  Rename
	"set/show debug dwarf2-die" to "set/show debug dwarf-die".

gdb/doc/ChangeLog:

	* gdb.texinfo (Debugging Output): Update for DWARF "set debug"
	command renamings.
	(Maintenance Commands): Update for DWARF "set debug" command renamings.

gdb/testsuite/ChangeLog:

	* gdb.dwarf2/dw2-op-call.exp: Update.
	* gdb.dwarf2/dw4-sig-types.exp: Update.
	* gdb.dwarf2/implptr.exp: Update.
	* gdb.mi/mi-cmd-param-changed.exp: Update.