In change #146863 we moved definitions of preinit/init/fini arrays to
header but unintentionally moved outside of the namespace. Since the
namespace also controls the visibility (through LIBC_NAMESPACE_DECL), as
a consequence these symbols no longer have the hidden visibility which
changes the codegen from:
```
4: 4c11 ldr r4, [pc, #0x44] @ 0x4c <__libc_init_array+0x4c>
6: 4812 ldr r0, [pc, #0x48] @ 0x50 <__libc_init_array+0x50>
8: 447c add r4, pc
a: 4478 add r0, pc
c: 1b00 subs r0, r0, r4
```
to:
```
4: 4813 ldr r0, [pc, #0x4c] @ 0x54 <__libc_init_array+0x54>
6: 4914 ldr r1, [pc, #0x50] @ 0x58 <__libc_init_array+0x58>
8: 4478 add r0, pc
a: 4479 add r1, pc
c: 6804 ldr r4, [r0]
e: 6808 ldr r0, [r1]
10: 1b00 subs r0, r0, r4
```
The `ldr` will trigger a fault in case where these symbols aren't
pointing to a valid memory location which is sometimes the case when the
array is empty.
5bf399ba95