* gold.h (gold_undefined_symbol): Change to take only a Symbol
pointer and to report location as the file name associated with
the symbol.
(gold_undefined_symbol_at_location): New function to replace the
old gold_undefined_symbol functionality.
* target-reloc.h (relocate_section): Update to use
gold_undefined_symbol_at_location.
* symtab.cc (Symbol_table::warn_about_undefined_dynobj_symbol):
Call gold_undefined_symbol function rather than gold_error.
* errors.h (Errors::undefined_symbol): Take location as a
string, rather than calculating it from a relocation.
* errors.cc (Errors::fatal): Print "fatal error:" before the
formatted message.
(Errors::error, Errors::error_at_location): Print "error: "
before the formatted message.
(Errors::undefined_symbol): Take location as a string, rather
than calculating it from a relocation.
(gold_undefined_symbol_at_location): New function akin to
old gold_undefined_symbol, calculates location from relocation.
(gold_undefined_symbol): Change to take only a Symbol pointer
and to report location as the file name associated with the symbol.
* testsuite/debug_msg.sh: Update for changed error messages.
* testsuite/undef_symbol.sh: Likewise.
