PR gold/11317

	PR gold/11317
	* target-reloc.h (issue_undefined_symbol_error): New inline
	function, broken out of relocate_section.
	(relocate_section): Call issue_undefined_symbol_error.
	* i386.cc (Target_i386::Relocate::relocate_tls): Don't crash if
	there is no TLS segment if we are about to issue an undefined
	symbol error.
	* x86_64.cc (Target_x86_64::relocate_tls): Likewise.