autotools example: m4 segmentation fault

```
❯ bazel build @m4//...
...
bazel-out/darwin_arm64-fastbuild/bin/external/m4/m4_foreign_cc/build_script.sh: line 102: 87922 Segmentation fault: 11 $EXT_BUILD_ROOT/bazel-out/darwin_arm64-opt-exec-2B5CBBC6/bin/external/rules_foreign_cc/toolchains/make/bin/make -C $BUILD_TMPDIR
...
```

Start by reproducing `bazel build @m4//...` on the reported Darwin ARM64 setup. Then inspect `bazel-out/darwin_arm64-fastbuild/bin/external/m4/m4_foreign_cc/build_script.sh` at line 102 and the referenced `make` invocation; done means the example builds without a segmentation fault.

Written by the indexing model from the issue text.