Add genf90 resource for cprnc to allow offline builds (spack#42015)

* Add genf90 resource for cprnc to allow offline builds
* Update package.py
* Update package.py style fix

Author: AlexanderRichert-NOAA

var/spack/repos/builtin/packages/cprnc/package.py

@@ -22,3 +22,17 @@ class Cprnc(CMakePackage):
 
     depends_on("netcdf-fortran")
     depends_on("cmake@3:", type="build")
+
+    resource(
+        name="genf90",
+        git="https://github.com/PARALLELIO/genf90",
+        tag="genf90_200608",
+        destination="genf90-resource",
+    )
+
+    def cmake_args(self):
+        args = [
+            self.define("GENF90_PATH", join_path(self.stage.source_path, "genf90-resource/genf90"))
+        ]
+
+        return args