easyloggingpp: Update version to 9.97.1

Update to version 9.97.1 of easyloggingpp

Changelog from upstream
* Ensuring the build on ARM64 works
* Update gtest and cmake now requires C++14 because of that

Compile tested: arm_cortex-a7_neon-vfpv4, mips_24kc, aarch64_cortex-a53

Run tested: Linksys MR8300 (arm_cortex-a7_neon-vfpv4)
            GL.iNet GL-A1800 (arm_cortex-a7_neon-vfpv4)
            TP-Link_Archer A7 (mips_24kc),
            GL.iNet GL-MT3000 (aarch64_cortex-a53)

Signed-off-by: Volker Christian <me@vchrist.at>
(cherry picked from commit d8df885ac6427e3c14fde62bbcaf31a6fb91128f)

libs/easyloggingpp/Makefile

 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=easyloggingpp
-PKG_VERSION:=9.97.0
+PKG_VERSION:=9.97.1
 PKG_RELEASE:=1
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://codeload.github.com/abumq/easyloggingpp/tar.gz/v$(PKG_VERSION)?
-PKG_HASH:=9110638e21ef02428254af8688bf9e766483db8cc2624144aa3c59006907ce22
+PKG_HASH:=ebe473e17b13f1d1f16d0009689576625796947a711e14aec29530f39560c7c2
 
 PKG_MAINTAINER:=Volker Christian <me@vchrist.at>
 PKG_LICENSE:=MIT