Add basic CI

.gitlab-ci.yml

+variables:
+  CCACHE_COMPILERCHECK: content
+  CCACHE_DIR: "${CI_PROJECT_DIR}/.ccache"
+
+
+build:
+  stage: build
+  image: alpine:latest
+  tags: [docker]
+  before_script:
+    - sed -i '/edge/s/^#//' /etc/apk/repositories
+    - apk update && apk add clang-extra-tools meson git python3 py3-pip py3-flask lcov gcovr libcurl libevent grep
+    - export PATH="$PATH:/root/.local/bin"
+    - pip3 install --user reuse
+  script:
+    - meson setup builddir -Db_coverage=true -Dtests=true -Dexamples=true
+    - meson compile -C builddir
+    - ./scripts/run_tls_testserver.sh &
+    - ./builddir/tests/requests_tls -d
+    - ninja -C builddir coverage-text
+    - grep TOTAL builddir/meson-logs/coverage.txt