gold: Always resolve non-default weak undefined to 0

Non-default weak undefined symbols in executable and shared library are
always resolved to 0 at runtime and don't need dynamic relocation.

Tested on i686, x86-64, powerpc64le and aarch64.

	PR gold/32071
	* symtab.cc (Symbol::final_value_is_known): Always resolve
	non-default weak undefined symbol in executable and shared library
	to 0 at runtime.
	* symtab.h (Symbol::needs_dynamic_reloc): Return false for
	non-default weak undefined symbol in executable and shared library.
	* testsuite/Makefile.am: Add weak_undef_test_3 and
	weak_undef_test_4 tests.
	* testsuite/Makefile.in: Regenerated.
	* testsuite/weak_undef_lib_4.c: New file.
	* testsuite/weak_undef_test_3.c: Likewise.
	* testsuite/weak_undef_test_4.c: Likewise.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
7 files changed