AutotoolsPackage: minor improvements (#2859)

* AutotoolsPackage: added configure_directory to permit build out of source. The configure script executable is now invoked with an absolute path. Modified a few packages accordingly.

* build_systems: functions returning directories are now properties

* build_systems: fixed issues with tcl and tk

* AutotoolsPackage: reworked recipe for autoreconf

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

@@ -39,6 +39,7 @@ class Astyle(MakefilePackage):
 
     parallel = False
 
+    @property
     def build_directory(self):
         return join_path(self.stage.source_path, 'build', self.compiler.name)