Comment 1 for bug 1693289

For a complete example, compile with clang >= 4.0:

```
static volatile int foo = 0;

void _start() {
  while (foo != 1) {
    asm volatile ("nop");
  }
}
```

$ clang -fropi -frwpi --target=thumbv7-eabi -c -o test.o test.c
$ arm-none-eabi-ld test.o -o test
test.o: In function `_start':
test.c:(.text+0x28): dangerous relocation: unsupported relocation

I believe the fix would be somewhere in

static bfd_reloc_status_type elf32_arm_final_link_relocate

starting on line 9872 in `bfd/elf32-arm.c`