New comment by pullmoll on void-packages repository

https://github.com/void-linux/void-packages/pull/12360#issuecomment-500254154
Comment:
Trying to build `strace` for `ppc-musl` or `ppc64-musl` with this PR's `libunwind` and `libucontext` gives me an error:
```
…
checking libunwind-ptrace.h usability... yes
checking libunwind-ptrace.h presence... yes
checking for libunwind-ptrace.h... yes
checking for backtrace in -lunwind... no
configure: error: in `/builddir/strace-5.1':
configure: error: failed to find libunwind
See `config.log' for more details
=> ERROR: strace-5.1_1: do_configure: '${configure_script} ${configure_args}' exited with 1
=> ERROR:   in do_configure() at common/build-style/gnu-configure.sh:7
```
I don't know if perhaps `libunwind` for `*-musl` should `makedepends+=" libexecinfo-devel"`...