objtool/klp: Fix relocation conversion failures for R_X86_64_NONE

Objtool has some hacks which NOP out certain calls/jumps and replace
their relocations with R_X86_64_NONE.  The klp-diff relocation
extraction code will error out when trying to copy these relocations due
to their negative addend, which would only makes sense for a PC-relative
branch instruction.  Just ignore them.

Fixes: dd590d4d57 ("objtool/klp: Introduce klp diff subcommand for diffing object files")
Acked-by: Song Liu <song@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

tools/objtool/klp-diff.c

@@ -1033,6 +1033,9 @@ found_sym:
  */
 static int convert_reloc_sym(struct elf *elf, struct reloc *reloc)
 {
+	if (reloc_type(reloc) == R_NONE)
+		return 1;
+
 	if (is_reloc_allowed(reloc))
 		return 0;