I used the new flag in the i386 and amd64 kernel builds, see
D16749 and D16750. With this optimization ifunc calls look
the same as any others:
```
(kgdb) disas fuword
Dump of assembler code for function fuword:
0xffffffff80799b50 <fuword+0>: push %rbp
0xffffffff80799b51 <fuword+1>: mov %rsp,%rbp
0xffffffff80799b54 <fuword+4>: sub $0x10,%rsp
0xffffffff80799b58 <fuword+8>: lea -0x8(%rbp),%rsi
0xffffffff80799b5c <fuword+12>: callq 0xffffffff80adc4a0 <fueword_nosmap>
0xffffffff80799b61 <fuword+17>: mov %eax,%ecx
0xffffffff80799b63 <fuword+19>: mov $0xffffffffffffffff,%rax
0xffffffff80799b6a <fuword+26>: cmp $0xffffffffffffffff,%ecx
0xffffffff80799b6d <fuword+29>: je 0xffffffff80799b73 <fuword+35>
0xffffffff80799b6f <fuword+31>: mov -0x8(%rbp),%rax
0xffffffff80799b73 <fuword+35>: add $0x10,%rsp
0xffffffff80799b77 <fuword+39>: pop %rbp
0xffffffff80799b78 <fuword+40>: retq
```