Don't allow COPY relocations for protected symbols.

Don't allow COPY relocations for protected symbols.

gold/
	PR gold/19823
	* copy-relocs.cc (Copy_relocs::make_copy_reloc): Add object
	parameter; check for protected symbol.
	* copy-relocs.h (Copy_relocs::make_copy_reloc): Add object parameter.
	* mips.cc (Mips_copy_relocs): Adjust call to make_copy_reloc.
	* symtab.cc (Symbol::init_fields): Initialize is_protected_.
	(Symbol_table::add_from_dynobj): Mark protected symbols.
	* symtab.h (Symbol::is_protected): New method.
	(Symbol::set_is_protected): New method.
	(Symbol::is_protected_): New data member.

	* testsuite/Makefile.am (copy_test_protected): New test.
	* testsuite/Makefile.in: Regenerate.
	* testsuite/copy_test.cc (main): Add legal reference to protected
	symbol.
	* testsuite/copy_test_v1.cc (main): Likewise.
	* testsuite/copy_test_2.cc (ip): Add protected symbol.
	* testsuite/copy_test_protected.cc: New test source file.
	* testsuite/copy_test_protected.sh: New test script.