add M1 build with compilers from macports

.cirrus.yml

@@ -1,6 +1,18 @@
 macos_instance:
   image: ghcr.io/cirruslabs/macos-ventura-xcode:latest
 
+task:
+  name: AppleM1/MacPorts
+  compile_script:
+  - wget https://github.com/macports/macports-base/releases/download/v2.8.1/MacPorts-2.8.1-13-Ventura.pkg
+  - installer -verboseR -pkg MacPorts-2.8.1-13-Ventura.pkg
+  - port install gcc-devel
+  - port install llvm-16
+  - export PATH=/opt/local/bin:$PATH
+  - export LDFLAGS="-L/opt/local/lib"
+  - export CPPFLAGS="-I/opt/local/include"
+  - make TARGET=VORTEX CC=clang FC=gfortran
+
 task:
   name: AppleM1/LLVM
   compile_script: