extend.texi (tls_model): Document.

extend.texi (tls_model): Document.

	* doc/extend.texi (tls_model): Document.
	* varasm.c (decl_tls_model): New.
	* c-common.c (handle_tls_model_attribute): New.
	(c_common_attribute_table): Add tls_model.
	* config/alpha/alpha.c (alpha_encode_section_info): Use
	decl_tls_model.
	* flags.h (enum tls_model, flag_tls_default): Move...
	* tree.h (enum tls_model, flag_tls_default): ...here.
	(decl_tls_model): New prototype.
	* config/ia64/ia64.c (ia64_encode_section_info): Likewise.
	* config/i386/i386.c (ix86_encode_section_info): Likewise.
	* config/i386/i386.md (tls_global_dynamic, tls_local_dynamic_base):
	Allow !flag_pic.

From-SVN: r57588