[m-rev.] for review: Pass compiler flags to build bdwgc for musl.

[Julien Fischer]

Hi Peter,

On Thu, 21 Sep 2017, Peter Wang wrote:

> The version of bdwgc we have now works with musl libc to some degree.
> I am waiting for the next release for bdwgc before upgrading our copy;
> that will fix parallel marking and possibly other problems.
>
> configure.ac:
> Mmake.common.in:
>    Check for functions getcontext and dl_iterate_phdr.
>
>    Add -DNO_GETCONTEXT to BOEHM_CFLAGS if getcontext does not exist.
>
>    Add -DHAVE_DL_ITERATE_PHDR to BOEHM_CFLAGS if dl_iterate_phdr does
>    exist.

That's fine.

Julien.