Fails to build with 4.9 & musl libc

[jku]

pppol2tp plugin fails to build with linux 4.9 headers and musl libc with:

| In file included from pppol2tp.c:34:0:
| /usr/include/linux/if.h:97:2: error: expected identifier before numeric constant
|   IFF_LOWER_UP   = 1<<16, /* __volatile__ */

I've fixed this locally by removing #include <linux/if_pppox.h> from openl2tp.c and pppol2tp.c as the include isn't actually needed, but I'm unsure whether this is the fix you'd like upstream... Let me know if you'd rather have a PR.

[Neustradamus]

@jku: The problem is always here in mainline and up-to-date linux kernel?

[jku]

Sorry, I wouldn't know: I've not compiled anything for musl in a few years.

[Neustradamus]

@jku: Ok :/

[RICCIARDI-Adrien]

Hi,
This issue might be closed now that musl support has been merged (see 7555728).

[Neustradamus]

@yegorich, @mjeveritt, @Polynomial-C, @RICCIARDI-Adrien, @jku: Have you tested, perfect for you?

Linked to:

• MUSL build breakage #51
• Improve musl libc Linux build without breaking other systems compatibility #110
• 7555728

[mjeveritt]

@mjeveritt: Have you tested, perfect for you?

Linked to:

* #51
* #110
* [7555728](https://github.com/paulusmack/ppp/commit/7555728c50db87ae7d5b8c018c006a14bf374584)

I can't speak to #51 at this stage, but the other two are definitely covered in Gentoo musl's patch here .

Tangentially I'm helping with #111 so that we can eliminate many of the Gentoo 'glibc'/vanilla patches for ppp, since we were looking to merge musl support into the main ::gentoo repository anyway. This will be a good tidy-up for the distro 😄 .