[compiler-rt] Add missing extendhfxf2 in compiler rt (PR #109090)

[B I Mohammed Abbas via llvm-commits]

biabbas wrote:

Object file preview with the change in 34a812421f03c888cb7fbf3b7f27b4732c99afe8. 
```
0000000000000170 <__extendhfxf2>:
 170:   50                      push   %rax
 171:   66 0f c5 c0 00          pextrw $0x0,%xmm0,%eax
 176:   66 89 44 24 06          mov    %ax,0x6(%rsp)
 17b:   66 0f c4 44 24 06 00    pinsrw $0x0,0x6(%rsp),%xmm0
 182:   e8 99 fe ff ff          call   20 <__extendXfYf2__>
 187:   f3 0f 11 04 24          movss  %xmm0,(%rsp)
 18c:   d9 04 24                flds   (%rsp)
 18f:   58                      pop    %rax
 190:   c3                      ret    
 191:   66 66 66 66 66 66 2e    data16 data16 data16 data16 data16 cs nopw 0x0(%rax,%rax,1)
 198:   0f 1f 84 00 00 00 00 
 19f:   00 
```

https://github.com/llvm/llvm-project/pull/109090