Test gcc-4.8 as part of CI (open-telemetry#19)

* Add CI test for gcc48.

* Add gcc_48_test to circleci

* Use bazel to test old compiler.

* Fix gcc-48 CI.

* Use CC instead of CXX

.circleci/config.yml

@@ -17,6 +17,17 @@ jobs:
           path: ~/build/Testing/Temporary/LastTest.log
           destination: Test.log
 
+  gcc_48_test:
+    resource_class: xlarge
+    docker:
+      - image: ubuntu:18.04
+    steps:
+      - checkout
+      - run: ./ci/setup_ci_environment.sh
+      - run: ./ci/install_bazelisk.sh
+      - run: ./ci/install_gcc48.sh
+      - run: CC=/usr/bin/g++-4.8 ./ci/do_ci.sh bazel.test
+
   bazel_test:
     resource_class: xlarge
     docker:
@@ -48,6 +59,7 @@ workflows:
   build_and_test:
     jobs:
       - cmake_test
+      - gcc_48_test
       - bazel_test
       - osx_test
       - windows

ci/Dockerfile

@@ -8,4 +8,5 @@ ADD install_bazelisk.sh /setup-ci
 
 RUN /setup-ci/setup_ci_environment.sh \
   && /setup-ci/setup_cmake.sh \
+  && /setup-ci/install_gcc48.sh \
   && /setup-ci/install_bazelisk.sh

ci/install_gcc48.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+set -e
+apt-get update 
+apt-get install --no-install-recommends --no-install-suggests -y \
+  g++-4.8