gdb/

gdb/
	Fix entry-values in C++ across CUs.
	* dwarf2loc.c (call_site_to_target_addr) <FIELD_LOC_KIND_PHYSNAME>: Use
	lookup_minimal_symbol.  Add a comment.
	* dwarf2read.c
	(read_call_site_scope) <is_ref_attr> <die_is_declaration>: Prefer
	DW_AT_linkage_name.

gdb/testsuite/
	Fix entry-values in C++ across CUs.
	* gdb.arch/amd64-tailcall-cxx.exp: New file.
	* gdb.arch/amd64-tailcall-cxx1.S: New file.
	* gdb.arch/amd64-tailcall-cxx1.cc: New file.
	* gdb.arch/amd64-tailcall-cxx2.S: New file.
	* gdb.arch/amd64-tailcall-cxx2.cc: New file.