add first CI: build with gcc/openmpi

.gitlab-ci.yml

+variables:
+  GIT_SUBMODULE_STRATEGY: recursive
+
+stages:
+  - build
+
+build:
+  stage: build
+  before_script:
+    - eval $(ssh-agent -s)
+    - ssh-keyscan git.mpimet.mpg.de >> ~/.ssh/known_hosts
+#   - ssh -vT git@git.mpimet.mpg.de
+    - ls /sw/rhel6-x64
+    - . /sw/rhel6-x64/etc/profile.mistral && module list
+  script:
+    - /sw/rhel6-x64/gcc/gcc-6.4.0/bin/gcc --version
+    - echo $USER
+    - echo $HOME
+    - echo $PATH
+    - pwd
+    - module load gcc/6.4.0
+    - module load openmpi/2.0.2p2_hpcx-gcc64
+    - mpif90 --version
+    - mpicc --version
+    - mpirun --help
+    - mkdir gcc64 && ../configure CC=mpicc FC=mpif90 --enable-mpi --disable-cdi-app --enable-iso-c-interface 
+  artifacts:
+    paths:
+      - gcc64/config.log
+    expire_in: 5min
+
+  tags:
+  - mistral
+
+  only:
+  - gitlab-ci
+