[s390x] dsymutil output is malformed on big-endian hosts

Build bot failure: https://lab.llvm.org/buildbot/#/builders/98/builds/2804
```
/home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/bin/dsymutil /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/test/tools/dsymutil/AArch64/Output/pseudo-probe.test.tmp/main.o -o /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/test/tools/dsymutil/AArch64/Output/pseudo-probe.test.tmp/main.dSYM
# executed command: /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/bin/dsymutil /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/test/tools/dsymutil/AArch64/Output/pseudo-probe.test.tmp/main.o -o /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/test/tools/dsymutil/AArch64/Output/pseudo-probe.test.tmp/main.dSYM
# .---command stderr------------
# | warning: no debug symbols in executable (-arch arm64)
# | error: /home/uweigand/sandbox/buildbot/clang-s390x-linux-multistage/stage2/test/tools/dsymutil/AArch64/Output/pseudo-probe.test.tmp/main.dSYM/Contents/Resources/DWARF/main.o: truncated or malformed object (load command 3 extends past end of file)
# `-----------------------------
# error: command failed with exit status: 1
```

After landing https://github.com/llvm/llvm-project/pull/186877 we get the above error only on s390x big endian hosts. I'm unable to recreate the problem.

Adding `REQUIRES: host-byteorder-little-endian` as a work around to unblock the s390x builedbot.