Add PnetCDF and M4 packages

var/spack/repos/builtin/packages/m4/package.py

@@ -0,0 +1,13 @@
+from spack import *
+
+class M4(Package):
+    """GNU M4 is an implementation of the traditional Unix macro processor."""
+    homepage = "https://www.gnu.org/software/m4/m4.html"
+    url      = "ftp://ftp.gnu.org/gnu/m4/m4-1.4.17.tar.gz"
+
+    version('1.4.17', 'a5e9954b1dae036762f7b13673a2cf76')
+
+    def install(self, spec, prefix):
+        configure("--prefix=%s" % prefix)
+        make()
+        make("install")