ci: use common execution script for all images

.gitlab-ci.yml

+# common script for all images
+.run-scripts: &run-scripts
+  - export LINUX=/lib/modules/$KVERSION/build
+  - export BUILD_DIR=$(mktemp -d)
+  - echo "Building under $BUILD_DIR"
+  - cd scripts
+  - bash wrtd_ref_spec150t_adc_install.sh
+  - bash wrtd_ref_svec_tdc_fd_install.sh
+  - for script in *.sh; do bash $script; done
+
 #Arch Linux:
 #  image: archlinux:latest
 #  script:
@@ -25,13 +35,7 @@ Ubuntu 18.04 LTS:
       linux-image-$KVERSION linux-modules-extra-$KVERSION linux-headers-$KVERSION python
       python-setuptools python-yaml python-decorator
       lua5.1 curl libreadline-dev
-    - export LINUX=/lib/modules/$KVERSION/build
-    - export BUILD_DIR=$(mktemp -d)
-    - echo "Building under $BUILD_DIR"
-    - cd scripts
-    - bash wrtd_ref_spec150t_adc_install.sh
-    - bash wrtd_ref_svec_tdc_fd_install.sh
-    - for script in *.sh; do bash $script; done
+  script: *run_scripts
 
 Debian Buster:
   image: debian:buster
@@ -42,13 +46,8 @@ Debian Buster:
       linux-image-amd64 linux-headers-amd64 python
       python-setuptools python-yaml python-decorator
       lua5.1 curl libreadline-dev
-    - export LINUX=/lib/modules/$KVERSION/build
-    - export BUILD_DIR=$(mktemp -d)
-    - echo "Building under $BUILD_DIR"
-    - cd scripts
-    - bash wrtd_ref_spec150t_adc_install.sh
-    - bash wrtd_ref_svec_tdc_fd_install.sh
-    - for script in *.sh; do bash $script; done
+    - export KVERSION=$(ls /lib/modules/)
+  script: *run_scripts
 
 CentOS 7:
   image: centos:7
@@ -63,10 +62,4 @@ CentOS 7:
       git sudo gcc make readline-devel patch
       python-setuptools python-yaml python-decorator
     - export KVERSION=$(basename /lib/modules/*plus*)
-    - export LINUX=/lib/modules/$KVERSION/build
-    - export BUILD_DIR=$(mktemp -d)
-    - echo "Building under $BUILD_DIR"
-    - cd scripts
-    - bash wrtd_ref_spec150t_adc_install.sh
-    - bash wrtd_ref_svec_tdc_fd_install.sh
-    - for script in *.sh; do bash $script; done
+  script: *run_scripts