Drop PowerPC 64 support (ppc64le) (jenkinsci#293)

IBM no longer provides the PowerPC agents that we use to test and
verify PowerPC support. Can't support an architecture that we can't
test.

Author: MarkEWaite

Makefile

@@ -8,7 +8,7 @@ export DOCKER_CLI_EXPERIMENTAL=enabled
 export BUILDKIT_PROGRESS=plain
 
 current_arch := $(shell uname -m)
-export ARCH ?= $(shell case $(current_arch) in (x86_64) echo "amd64" ;; (i386) echo "386";; (aarch64|arm64) echo "arm64" ;; (armv6*) echo "arm/v6";; (armv7*) echo "arm/v7";; (ppc64*|s390*|riscv*) echo $(current_arch);; (*) echo "UNKNOWN-CPU";; esac)
+export ARCH ?= $(shell case $(current_arch) in (x86_64) echo "amd64" ;; (i386) echo "386";; (aarch64|arm64) echo "arm64" ;; (armv6*) echo "arm/v6";; (armv7*) echo "arm/v7";; (s390*|riscv*) echo $(current_arch);; (*) echo "UNKNOWN-CPU";; esac)
 
 IMAGE_NAME:=jenkins4eval/agent
 IMAGE_NAME_AGENT:=jenkins4eval/slave

docker-bake.hcl

@@ -28,10 +28,6 @@ group "linux-s390x" {
   ]
 }
 
-group "linux-ppc64le" {
-  targets = []
-}
-
 group "windows" {
   targets = [
     "windows_2019_jdk11",