Massive conversion from Package to AutotoolsPackage (#2845)

* Massive conversion from Package to AutotoolsPackage

* Forgot to convert p4est to AutotoolsPackage

* Fix typo

* Fix broken link in docs

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

@@ -25,15 +25,10 @@
 from spack import *
 
 
-class Libunwind(Package):
+class Libunwind(AutotoolsPackage):
     """A portable and efficient C programming interface (API) to determine
        the call-chain of a program."""
     homepage = "http://www.nongnu.org/libunwind/"
     url      = "http://download.savannah.gnu.org/releases/libunwind/libunwind-1.1.tar.gz"
 
     version('1.1', 'fb4ea2f6fbbe45bf032cd36e586883ce')
-
-    def install(self, spec, prefix):
-        configure("--prefix=" + prefix)
-        make()
-        make("install")