libatomic linking needed on some platforms

[neheb]

Example failure: https://downloads.openwrt.org/snapshots/faillogs/arc_arc700/packages/udpspeeder/compile.txt

Missing -latomic.

(I don't speak Chinese)

[codemarauder]

@neheb I am maintainer for UDPSpeeder on OpenWrt. The Makefile contains following:

DEPENDS:= +libstdcpp +librt +libatomic

I need to test compilation on master again.

[codemarauder]

Below are the logs from build for x86_64 on my machine for master. @neheb is it failing for any specific architecture?

Generating index for package ./UDPspeeder_20210116.0-2_x86_64.ipk
Signing package index...