[PATCH v3 5/8] Add tdesc osabi and architecture functions

[PATCH v3 5/8] Add tdesc osabi and architecture functions

Add functions to access to printable names for osabi and architecture in
target_desc.

I wanted to add these as member functions of target_desc, but cannot until
target_desc is moved into the header files.

Alan.

2018-03-01  Alan Hayward  <alan.hayward@arm.com>

gdb/
	* common/tdesc.h (tdesc_architecture_name): Add new declaration.
	(tdesc_osabi_name): Likewise.
	* target-descriptions.c (tdesc_architecture_name): Add new function.
	(tdesc_osabi_name): Likewise.

gdb/gdbserver/
	* tdesc.c (tdesc_architecture_name): Add new function.
	(tdesc_osabi_name): Likewise.
	(tdesc_get_features_xml): Use new functions.