Move dwarf_always_disassemble to dwarf2/loc.c

Move dwarf_always_disassemble to dwarf2/loc.c

dwarf_always_disassemble is only used in dwarf2/loc.c, so move the
definition and the command infrastructure to that file.

2020-02-08  Tom Tromey  <tom@tromey.com>

	* dwarf2/read.c (dwarf_always_disassemble)
	(show_dwarf_always_disassemble): Move to loc.c.
	(_initialize_dwarf2_read): Move "always-disassemble" registration
	to loc.c.
	* dwarf2/read.h (dwarf_always_disassemble): Don't declare.
	* dwarf2/loc.c (dwarf_always_disassemble): Move from read.c.  Now
	static.
	(show_dwarf_always_disassemble): Move from read.c.
	(_initialize_dwarf2loc): Move always-disassemble from read.c.

Change-Id: I33fb88112e98e583c3f4919d20e4d100f2ea0124