libsframe: bump version to 2.0

libsframe: bump version to 2.0

Remove LIBSFRAME_1.1, LIBSFRAME_1.0 nodes and add a new LIBSFRAME_2.0
node (non-inheritance version) to create new global versioned symbols.
Also announce libsframe.so.2 in NEWS.

New APIs:
     sframe_decoder_get_flags;
     sframe_decoder_get_offsetof_fde_start_addr;
     sframe_encoder_get_flags;
     sframe_encoder_get_offsetof_fde_start_addr;

Removed APIs: (already deprecated since X-2 release)
     sframe_get_funcdesc_with_addr;

APIs with changed semantics:
     sframe_decoder_get_funcdesc_v2;
     sframe_encoder_add_funcdesc_v2;
     sframe_encoder_write;

lisbframe/
	* libsframe.ver: Define new LIBSFRAME_2.0.
	* libtool-version: Bump the 'current' numeral to indicate a binary
	incompatible release.
include/
	* sframe-api.h (sframe_get_funcdesc_with_addr): Remove
	deprecated interface.
libsframe/
	* sframe.c (sframe_get_funcdesc_with_addr): Likewise.
binutils/
	* NEWS: Announce new versioned release of libsframe.