Starting with BRCM SAI 4.3.1.5 we see the following :ethtool not fount" error in syslog during boot up:
```
Jan 27 07:36:14.712472 str-s6100-acs-1 INFO syncd#/supervisord: syncd sh: 1:
Jan 27 07:36:14.712844 str-s6100-acs-1 INFO syncd#/supervisord: syncd ethtool: not found
Jan 27 07:36:14.713228 str-s6100-acs-1 INFO syncd#/supervisord: syncd #015
Jan 27 07:36:14.713840 str-s6100-acs-1 INFO syncd#syncd: [0] SAI_API_HOSTIF:_brcm_sai_hostif_speed_set:11894 cmd ethtool -s Ethernet39 speed 40000 rc:32512
Jan 27 07:36:14.717204 str-s6100-acs-1 NOTICE swss#orchagent: :- setHostIntfsOperStatus: Set operation status DOWN to host interface Ethernet39
Jan 27 07:36:14.717204 str-s6100-acs-1 NOTICE swss#orchagent: :- initPort: Initialized port Ethernet39
Jan 27 07:36:14.717204 str-s6100-acs-1 NOTICE swss#orchagent: :- initializePort: Initializing port alias:Ethernet36 pid:1000000000040
Jan 27 07:36:14.726793 str-s6100-acs-1 NOTICE swss#portsyncd: :- onMsg: nlmsg type:16 key:Ethernet36 admin:0 oper:0 addr:4c:76:25:f5:48:80 ifindex:75 master:0
Jan 27 07:36:14.727967 str-s6100-acs-1 NOTICE swss#portsyncd: :- onMsg: Publish Ethernet36(ok) to state db
Jan 27 07:36:14.729331 str-s6100-acs-1 NOTICE swss#orchagent: :- addHostIntfs: Create host interface for port Ethernet36
Jan 27 07:36:14.752398 str-s6100-acs-1 INFO syncd#/supervisord: syncd sh: 1: ethtool: not found#015
Jan 27 07:36:14.752689 str-s6100-acs-1 INFO syncd#syncd: [0] SAI_API_HOSTIF:_brcm_sai_hostif_speed_set:11894 cmd ethtool -s Ethernet36 speed 40000 rc:32512
Jan 27 07:36:14.756050 str-s6100-acs-1 NOTICE swss#orchagent: :- setHostIntfsOperStatus: Set operation status DOWN to host interface Ethernet36
Jan 27 07:36:14.757585 str-s6100-acs-1 NOTICE swss#orchagent: :- initPort: Initialized port Ethernet36
```
It seems that starting with BRCM SAI 4.2.1.5 syncd is using ethtool to set the host interface speed and since this ethtool was not part of the syncd Docker, we observe these "ethtool not found" issue.
- Why I did it
To upgrade brcm syncd to buster
- How I did it
Updated BCM SAI using kernel version 4.19.0-12 and debian 10 to support buster.
Updated syncd docker from stretch to buster in sonic-buildimage
- How to verify it
Ensured docker is running synd buster.
After upgrade, ensured all BGP peers and ip interfaces are up.
Ping to BGP neighbors is working fine.
**- Why I did it**
We were building a custom version of Supervisor because I had added patches to prevent hangs and crashes if the system clock ever rolled backward. Those changes were merged into the upstream Supervisor repo as of version 3.4.0 (http://supervisord.org/changes.html#id9), therefore, we should be able to simply install the vanilla package via pip. This will also allow us to easily move to Python 3, as Python 3 support was added in version 4.0.0.
**- How I did it**
- Remove Makefiles and patches for building supervisor package from source
- Install Python 3 supervisor package version 4.2.1 in Buster base container
- Also install Python 3 version of supervisord-dependent-startup in Buster base container
- Debian package installed binary in `/usr/bin/`, but pip package installs in `/usr/local/bin/`, so rather than update all absolute paths, I changed all references to simply call `supervisord` and let the system PATH find the executable to prevent future need for changes just in case we ever need to switch back to build a Debian package, then we won't need to modify these again.
- Install Python 2 supervisor package >= 3.4.0 in Stretch and Jessie base containers
Add the same mechanism I developed for the SwSS service in #2845 to the syncd service. However, in order to cause the SwSS service to also exit and restart in this situation, I developed a docker-wait-any program which the SwSS service uses to wait for either the swss or syncd containers to exit.
- This PR allows supervisord to log syncd exit events to syslog
- Syncd dockers now are built from docker-config-engine instead of docker-base
- Supervisord in all syncd dockers now call syncd_start.s which is installed by sonic-sairedis repo
- Consolidate config.sh and start.sh scripts into one script (start.sh)
- Solve issue #435 - All dockers now run supervisord as their ENTRYPOINT
- All stdout/stderr output from processes managed by supervisord is now sent to syslog instead of their own files
- Supervisord log messages are now also sent to syslog
- Removed unused smartmontools package from docker-platform-monitor
