easyloggingpp: Add package

easyloggingpp: Add package
Maintainer: me@vchrist.at
Compile tested: OpenWRT-23.05-rc2, arm_cortex-a7_neon-vfpv4, mips_24kc
Run tested: arm_cortex-a7_neon-vfpv4 (Linksys MR8300), mips_24kc (tplink_archer-a7), OpenWrt 23.05-rc2

Description:
Easylogging++ is single header efficient logging library for C++ applications. It is extremely powerful,
highly extendable and configurable to user's requirements.

Signed-off-by: Volker Christian <me@vchrist.at>
(cherry picked from commit 2611e7c798c2cc27f0cd1ffee410787e1b77eb7d)