[CircleCi] Fix build by using Ubuntu 18.04 as base

Author: wilzbach

.circleci/config.yml

@@ -3,8 +3,8 @@ jobs:
   build:
     working_directory: ~/druntime
     docker:
-      - image: circleci/node:4.8.2
-    parallelism: 2
+      - image: circleci/buildpack-deps:18.04
+    parallelism: 1
     steps:
       - checkout
       - run:

.circleci/run.sh

@@ -10,7 +10,7 @@ CIRCLE_PROJECT_REPONAME=${CIRCLE_PROJECT_REPONAME:-druntime}
 
 case $CIRCLE_NODE_INDEX in
     0) MODEL=64 ;;
-    1) MODEL=32 ;;
+    1) MODEL=32 ;; # broken - https://issues.dlang.org/show_bug.cgi?id=19116
 esac
 
 download() {
@@ -98,8 +98,7 @@ coverage() {
     # load environment for bootstrap compiler
     source "$(CURL_USER_AGENT=\"$CURL_USER_AGENT\" bash ~/dlang/install.sh dmd-$HOST_DMD_VER --activate)"
 
-    # build dmd and druntime (in debug and release)
-    make -j$N -C ../dmd/src -f posix.mak MODEL=$MODEL HOST_DMD=$DMD BUILD="debug" all
+    # build dmd (release) and druntime (debug)
     make -j$N -C ../dmd/src -f posix.mak MODEL=$MODEL HOST_DMD=$DMD BUILD="release" all
     TEST_COVERAGE="1" make -j$N -C . -f posix.mak MODEL=$MODEL unittest-debug
 }