Add builds.sr.ht CI for OpenBSD

* Add .builds/openbsd.yml for builds.sr.ht
* Update travis-build.sh -> ci-build.sh with OpenBSD case
* Fix libdl check in configure.ac (OpenBSD has libdl built-in)
* Fix some minor issues found when compiling on OpenBSD with GCC (e.g.
  uninitialized variables)

.travis.yml

@@ -31,15 +31,15 @@ matrix:
 
 before_install:
   - if [ "$TRAVIS_OS_NAME" = "linux" ]; then
-      docker build -f Dockerfile."$BUILD_FLAVOR" -t profanity .;
+    docker build -f Dockerfile."$BUILD_FLAVOR" -t profanity .;
     fi
 
 script:
   - if [ "$TRAVIS_OS_NAME" = "linux" ]; then
-      docker run -it profanity ./travis-build.sh;
+    docker run -it profanity ./ci-build.sh;
     fi
   - if [ "$TRAVIS_OS_NAME" = "osx" ]; then
-      ./travis-build.sh;
+    ./ci-build.sh;
     fi
 
 after_failure: