Merge bitcoin/bitcoin#29651: guix: bump time-machine to dc4842797bfdc5f9f3f5f725bf189c2b68bd6b5a

cf5faf73c9 guix: bump time-machine to dc4842797bfdc5f9f3f5f725bf189c2b68bd6b5a (fanquake)

Pull request description:

  This includes a commit to fix building LLVM 17 on riscv64, see https://git.savannah.gnu.org/cgit/guix.git/commit/?id=4e26331a5ee87928a16888c36d51e270f0f10f90.

  Followup to discussion in https://github.com/bitcoin/bitcoin/pull/28880#issuecomment-1843313196.

  If you don't have riscv64 hardware, this can be tested with the following:
  ```bash
  # observe failure when cross-compiling using our current time-machine
  guix time-machine --commit=d5ca4d4fd713a9f7e17e074a1e37dda99bbb09fc -- build --target=riscv64-linux-gnu  llvm
  ....
  riscv64-linux-gnu-ld: CMakeFiles/dsymutil.dir/dsymutil.cpp.o: undefined reference to symbol '__atomic_fetch_and_1@@LIBATOMIC_1.0'
  riscv64-linux-gnu-ld: /gnu/store/i4ga0pnr1b74bir2bjyp8mcrrbsvk7d3-gcc-cross-riscv64-linux-gnu-11.3.0-lib/riscv64-linux-gnu/lib/libatomic.so.1:
    error adding symbols: DSO missing from command line
  collect2: error: ld returned 1 exit status

  # build success when using the new time-machine
  guix time-machine --commit=dc4842797bfdc5f9f3f5f725bf189c2b68bd6b5a -- build --target=riscv64-linux-gnu  llvm
  ....
  grafting '/gnu/store/7y0j0y8jaz4mjx2nz0y42wdnxxjp6id6-llvm-17.0.6-opt-viewer' -> '/gnu/store/8xvahrrjscbprh6cjj0qp5bm9mm78wwa-llvm-17.0.6-opt-viewer'...
  grafting '/gnu/store/bjhw648bz7ijd2p9hgzzdbw1q8hpagk8-llvm-17.0.6' -> '/gnu/store/x50qi8i2ywgpx6azv4k55ms0w5xjxxg5-llvm-17.0.6'...
  successfully built /gnu/store/q9xvk8gzzvb4dxfzf6yi5164zd0d1vj2-llvm-17.0.6.drv
  ```

  Also includes at least:
  Linux Headers 6.1.67 -> 6.1.80

ACKs for top commit:
  TheCharlatan:
    ACK cf5faf73c9
  hebasto:
    ACK cf5faf73c9, tested on x86_64 hardware as described in the PR description.

Tree-SHA512: b49d4f90effeec666b12b5447a24c90315b82675cfc166bc1230ac173134bab6b277fc7e064bbb75e990275165b2b27d88e4ec1cdeea4750541ec6443cb50f41

contrib/guix/libexec/prelude.bash

@@ -51,7 +51,7 @@ fi
 time-machine() {
     # shellcheck disable=SC2086
     guix time-machine --url=https://git.savannah.gnu.org/git/guix.git \
-                      --commit=d5ca4d4fd713a9f7e17e074a1e37dda99bbb09fc \
+                      --commit=dc4842797bfdc5f9f3f5f725bf189c2b68bd6b5a \
                       --cores="$JOBS" \
                       --keep-failed \
                       --fallback \