cargo on ppc64 fails: invalid instruction: *EDIT*: on ntpdate as well
Description of problem:
Machine boots,
but when compiling a rust library, the following issue appears:
```
cargo  build --release --manifest-path rust-src/Cargo.toml
cargo[376]: illegal instruction (4) at 12e0933c0 nip 12e0933c0 lr 12dd7c768 code 1 in cargo[12dc10000+956000]
cargo[376]: code: 00000000 00000000 00000000 7c0802a6 f8010010 f821ff11 fba100d8 60000000 
cargo[376]: code: fbc100e0 8862cd50 28030000 418200d4 <104214c4> 38810070 3bc00000 7c4021ce 
make: *** [Makefile:133: rust-src/target/release/libbcachefs_rust.a] Illegal instruction (core dumped)
make: *** Waiting for unfinished jobs....
ar[375]: illegal instruction (4) at 3fff9b2a4dac nip 3fff9b2a4dac lr 3fff9b2a4da4 code 1 in libLLVM-16.so.1[3fff99f10000+792f000]
ar[375]: code: f87d0028 7fa3eb78 b29d0090 f89d0020 4810a8c1 60000000 7f83e378 7fa4eb78 
ar[375]: code: 7fc5f378 49bfd3e1 e8410028 60000000 <104214c4> 38810070 fb610080 eba29fe0 
make: *** [Makefile:129: libbcachefs.a] Illegal instruction (core dumped)
make: *** Deleting file 'libbcachefs.a'
```
the core dump files of cargo and ar are attached

~~I have no clue whether this is a rustc or qemu bug, so please let me know if this issue should be forwarded to rust devs~~
EDIT: as this happens with ntpdate as well, I think it's an emulator issue:

```
ntpdig[1179]: illegal instruction (4) at 102382c4 nip 102382c4 lr 102382a8 code 1 in python3.11[10000000+63e000]
ntpdig[1179]: code: 3d22ffdd c8094448 fc1e0000 41c2022c 4bde9b5d e8410028 3d42ffdd 39200000 
ntpdig[1179]: code: c80a4450 91230000 fc1e0000 41c001a4 <ffe0f02c> fc1ff800 41c30280 3d22ffdd 
```
Steps to reproduce:
1. create a debian ppc64 root image using debian sid & debootstrap
2. install rust using rustup
3. compile bcachefs-tools in ppc64

2b. Install ntpdate using apt-get ntpdate
3b. run ntpdate
Additional information:
Core dump command:
```
cat /proc/sys/kernel/core_pattern
|/bin/cp --sparse=always /dev/stdin /host//repos/janpieter/linux/bcachefs/ktest-out/core.%e.PID%p.SIG%s.TIME%t
```


[core.ar.PID374.SIG4.TIME1696070088.xz](/uploads/6a540c4d13351871b1e22153ad87ab99/core.ar.PID374.SIG4.TIME1696070088.xz) AR core dump

[core.ar.PID375.SIG4.TIME1696070088.xz](/uploads/7c314eba58c2190e3a9fbd88f8eb1242/core.ar.PID375.SIG4.TIME1696070088.xz) AR core dump

[core.cargo.PID375.SIG4.TIME1696070087.xz](/uploads/0097d457eb2d25e0123874b59405647a/core.cargo.PID375.SIG4.TIME1696070087.xz) cargo core dump 

[core.cargo.PID376.SIG4.TIME1696070087.xz](/uploads/53834fa9608036d6de9dafc3f778f165/core.cargo.PID376.SIG4.TIME1696070087.xz) cargo core dump

[core.ntpdig.PID1171.SIG4.TIME1696070657.xz](/uploads/8a96d86338d7c6bebe39657a24f570d8/core.ntpdig.PID1171.SIG4.TIME1696070657.xz) ntpdig core dump