Dockerfile for rhel8.2

- Made changes in commit aff11901 for build_helper,build_helper.fb_folly, build_helper.nrf to accomodate rhel8 linux support
- Removed buildconfig file which was only required for openshift cluster

docker/buildconfig.yaml

-apiVersion: image.openshift.io/v1
-kind: ImageStream
-metadata:
-   name: oai-nrf
-spec:
-  lookupPolicy:
-    local: true
----
-apiVersion: build.openshift.io/v1
-kind: BuildConfig
-metadata:
-  name: "oai-nrf"
-spec:
-    runPolicy: "Serial"
-    source:
-        type: "Binary"
-        secrets:
-          - secret:
-              name: etc-pki-entitlement
-            destinationDir: etc-pki-entitlement
-        configMaps:
-          - configMap:
-              name: rhsm-conf
-            destinationDir: rhsm-conf
-          - configMap:
-              name: rhsm-ca
-            destinationDir: rhsm-ca
-    strategy:
-        dockerStrategy:
-            dockerfilePath: "docker/Dockerfile.nrf.rhel8.2"
-            buildArgs:
-                - name: "NEEDED_GIT_PROXY"
-                  value: "http://proxy.eurecom.fr:8080"
-    output:
-        to:
-            kind: "ImageStreamTag"
-            name: "oai-nrf:develop"