Updating udunits version. (#2922)

* Updating udunits.

Udunits 2.2.21 is no longer on the unidata ftp site.
The latest is 2.2.23, adding that and it's md5sum.

* Updating udunits2 download URL.

The Unidata ftp site does not keep previous versions of udunits.
However all the tagged versions are in their github.com repository.
Updating the URL to use github.

* Updating udunits2 with a autoreconf def.

The udunits packages on github do not contain a configure script.
One has to run autoreconf to generate it, so adding that to
package file.

Also updated to the latest version and all md5 checksums.

var/spack/repos/builtin/packages/udunits2/package.py

@@ -29,11 +29,34 @@ class Udunits2(AutotoolsPackage):
     """Automated units conversion"""
 
     homepage = "http://www.unidata.ucar.edu/software/udunits"
-    url      = "ftp://ftp.unidata.ucar.edu/pub/udunits/udunits-2.2.21.tar.gz"
+    url      = "https://github.com/Unidata/UDUNITS-2/archive/v2.2.23.tar.gz"
 
-    version('2.2.21', '1f6d3375efc1f124790a4efb7102cdb7')
+    version('2.2.25', '373106a0fcd20c40fc53a975c9fa4fca')
+    version('2.2.24', '316911493e3b5c28ff7019223b4e27ea')
+    version('2.2.23', '0c0d9b1ebd7ad066233bedf40e66f1ba')
+    version('2.2.21', '167738b3ec886da1b92239de9cbbbc39')
 
     depends_on('expat')
 
     depends_on('bison', type='build')
     depends_on('flex',  type='build')
+    depends_on('libtool', type='build')
+    depends_on('automake', type='build')
+    depends_on('autoconf', type='build')
+    depends_on('pkg-config', type='build')
+
+    def autoreconf(self, spec, prefix):
+        # Work around autogen.sh oddities
+        # bash = which("bash")
+        # bash("./autogen.sh")
+        mkdirp("config")
+        autoreconf = which("autoreconf")
+        autoreconf("--install", "--verbose", "--force",
+                   "-I", "config",
+                   "-I", join_path(spec['pkg-config'].prefix,
+                                   "share", "aclocal"),
+                   "-I", join_path(spec['automake'].prefix,
+                                   "share", "aclocal"),
+                   "-I", join_path(spec['libtool'].prefix,
+                                   "share", "aclocal"),
+                   )