Add dwarf2_per_objfile parameters to dwarf2_fetch_* functions

This allows removing dwarf2_per_cu_data references.

gdb/ChangeLog:

	* dwarf2/read.h (dwarf2_fetch_die_loc_sect_off,
	dwarf2_fetch_die_loc_cu_off, dwarf2_fetch_constant_bytes,
	dwarf2_fetch_die_type_sect_off): Add dwarf2_per_objfile
	parameter.
	* dwarf2/read.c (dwarf2_fetch_die_loc_sect_off,
	dwarf2_fetch_die_loc_cu_off, dwarf2_fetch_constant_bytes,
	dwarf2_fetch_die_type_sect_off): Add dwarf2_per_objfile
	parameter.
	* dwarf2/loc.c (indirect_synthetic_pointer, per_cu_dwarf_call,
	sect_variable_value): Add dwarf2_per_objfile parameter.
	(class dwarf_evaluate_loc_desc) <dwarf_call,
	dwarf_variable_value>: Update.
	(fetch_const_value_from_synthetic_pointer): Add
	dwarf2_per_objfile parameter.
	(fetch_const_value_from_synthetic_pointer): Update.
	(coerced_pieced_ref): Update.
	(class symbol_needs_eval_context) <dwarf_call,
	dwarf_variable_value>: Update.
	(dwarf2_compile_expr_to_ax): Update.

Change-Id: I07cf1806380633d0572304cea049a1fa5e9ea67f