linker: don't fix up instructions without a Reference
linker: don't fix up instructions without a Reference

The kernel selftests contain the follwing assembly in test_get_stack_rawtp_err.o:

    ;	while (1) {
    6:	05 00 ff ff 00 00 00 00	goto -1 <LBB0_1>

which is generated for the following C snippet:

    while (1) {
        error++;
    }

Basically, the infinite loop is turned into a jump to -1, aka the
jump instruction itself. The linker currently interprets the -1 to
mean "requires relocation" and so gives a somewhat cryptic error.

Stop trying to fix up jumps and calls if they don't have a refernce.

cilium/ebpf,cilium/ebpf