setup_extension_environment is now setup_dependent_environment.

- other packages, like Qt, can now use this to set up relevant build
  variables and env vars for their dependencies.

- not just extensions anymore.

var/spack/packages/python/package.py

@@ -46,7 +46,7 @@ def site_packages_dir(self):
         return os.path.join(self.python_lib_dir, 'site-packages')
 
 
-    def setup_extension_environment(self, module, spec, ext_spec):
+    def setup_dependent_environment(self, module, spec, ext_spec):
         """Called before python modules' install() methods.
 
         In most cases, extensions will only need to have one line::

var/spack/packages/qt/package.py

@@ -1,3 +1,4 @@
+import os
 from spack import *
 
 class Qt(Package):
@@ -20,6 +21,11 @@ class Qt(Package):
     depends_on("libmng")
     depends_on("jpeg")
 
+    def setup_dependent_environment(self, module, spec, dep_spec):
+        """Dependencies of Qt find it using the QTDIR environment variable."""
+        os.environ['QTDIR'] = self.prefix
+
+
     def patch(self):
         # Fix qmake compilers in the default mkspec
         qmake_conf = 'mkspecs/common/g++-base.conf'