plugins/nd: Fix building with CFLAGS=-fno-common

[jer-gentoo]

With the GCC -fno-common flag, enabled by default in GCC >=10, the linker fails with messages like these:

ld: plugins/nd/1b87e75@@nd@sha/src_notification.c.o:(.bss+0x0): multiple definition of eventd_nd_backends_names'; plugins/nd/1b87e75@@nd@sha/src_nd.c.o:(.data.rel.local+0x20): first defined here ld: plugins/nd/1b87e75@@nd@sha/src_backends.c.o:(.bss+0x0): multiple definition ofeventd_nd_backends_names'; plugins/nd/1b87e75@@nd@sha/src_nd.c.o:(.data.rel.local+0x20): first defined here collect2: error: ld returned 1 exit status

Fix this by declaring eventd_nd_backends_names as extern.

Signed-off-by: Jeroen Roovers jer@gentoo.org

[sardemff7]

Thanks for the patch!

I’ll just be nitpicky on the commit message: although I don’t always succeed, I try to describe the actual issue in the summary for this kind of fixes. The flag breaking the build is a symptom here. I would go with “Avoid a possible multiple definition”, what do you think?

Also, I use "nd:" as the prefix (IOW, just the plugin name), "plugins:" is for commits that affects many plugins at once for a generic change.

[jer-gentoo]

I adjusted the commit message.

[sardemff7]

Perfect! Thanks again :-)