Fix struct, union, and enum nesting in C++

Fix struct, union, and enum nesting in C++

In C, an enum or structure defined inside other structure has global
scope just like it had been defined outside the struct in the first
place.  However, in C++, such a nested structure is given a name that
is nested inside the structure.  This patch moves such affected
structures/enums out to global scope, so that code using them works
the same in C++ as it works today in C.

gdb/ChangeLog:
2015-02-27  Tom Tromey  <tromey@redhat.com>
	    Pedro Alves  <palves@redhat.com>

	* dwarf2-frame.c (enum cfa_how_kind, struct
	dwarf2_frame_state_reg_info): Move out of struct
	dwarf2_frame_state.
	* dwarf2read.c (struct tu_stats): Move out of struct
	dwarf2_per_objfile.
	(struct file_entry): Move out of struct line_header.
	(struct nextfield, struct nextfnfield, struct fnfieldlist, struct
	typedef_field_list): Move out of struct field_info.
	* gdbtypes.h (enum dynamic_prop_kind, union dynamic_prop_data):
	Move out of struct dynamic_prop.
	(union type_owner, union field_location, struct field, struct
	range_bounds, union type_specific): Move out of struct main_type.
	(struct fn_fieldlist, struct fn_field, struct typedef_field)
	(VOFFSET_STATIC): Move out of struct cplus_struct_type.
	(struct call_site_target, union call_site_parameter_u, struct
	call_site_parameter): Move out of struct call_site.
	* m32c-tdep.c (enum m32c_prologue_kind): Move out of struct
	m32c_prologue.
	(enum srcdest_kind): Move out of struct srcdest.
	* main.c (enum cmdarg_kind): Move out of struct cmdarg.
	* prologue-value.h (enum prologue_value_kind): Move out of struct
	prologue_value.
	* s390-linux-tdep.c (enum s390_abi_kind): Move out of struct
	gdbarch_tdep.
	* stabsread.c (struct nextfield, struct next_fnfieldlist): Move
	out of struct field_info.
	* symfile.h (struct other_sections): Move out of struct
	section_addr_info.
	* symtab.c (struct symbol_cache_slot): Move out struct
	block_symbol_cache.
	* target-descriptions.c (enum tdesc_type_kind): Move out of
	typedef struct tdesc_type.
	* tui/tui-data.h (enum tui_line_or_address_kind): Move out of
	struct tui_line_or_address.
	* value.c (enum internalvar_kind, union internalvar_data): Move
	out of struct internalvar.
	* xtensa-tdep.h (struct ctype_cache): Move out of struct
	gdbarch_tdep.