Fix OpenBSD CI job

Author: Bodigrim

.cirrus.yml

@@ -15,7 +15,7 @@ task:
     # See https://github.com/anarazel/pg-vm-images/blob/main/packer/openbsd.pkrvars.hcl
     image: family/pg-ci-openbsd-vanilla
     platform: openbsd
-  install_script: pkg_add ghc cabal-install git autoconf-2.71
+  install_script: pkg_add ghc cabal-install git autoconf-2.71p0
   script:
     - export AUTOCONF_VERSION=2.71
     - export CABAL_DIR=/tmp/.cabal

unix.cabal

@@ -187,6 +187,11 @@ test-suite unix-tests
       build-depends: filepath >= 1.5.0.0, os-string >= 2.0.0
     else
       build-depends: filepath >= 1.4.100.0 && < 1.5.0.0
+
+    -- https://github.com/haskellari/splitmix/issues/101
+    if os(openbsd)
+      build-depends: splitmix < 0.1.3 || > 0.1.3.1
+
     ghc-options: -Wall -with-rtsopts=-V0
 
 test-suite FdReadBuf001