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/giflib/package.py

@@ -25,7 +25,7 @@
 from spack import *
 
 
-class Giflib(Package):
+class Giflib(AutotoolsPackage):
     """The GIFLIB project maintains the giflib service library, which has
     been pulling images out of GIFs since 1989."""
 
@@ -33,9 +33,3 @@ class Giflib(Package):
     url      = "https://downloads.sourceforge.net/project/giflib/giflib-5.1.4.tar.bz2"
 
     version('5.1.4', '2c171ced93c0e83bb09e6ccad8e3ba2b')
-
-    def install(self, spec, prefix):
-        configure('--prefix=%s' % prefix)
-
-        make()
-        make("install")