mixins: implemented declarative syntax

Implemented a declarative syntax for the additional behavior that can
get attached to classes. Implemented a function to filter compiler
wrappers that uses the mechanism above.

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

@@ -26,7 +26,7 @@
 import os
 
 
-class Mpich(AutotoolsPackage, mixins.FilterCompilerWrappers):
+class Mpich(AutotoolsPackage):
     """MPICH is a high performance and widely portable implementation of
     the Message Passing Interface (MPI) standard."""
 
@@ -71,6 +71,8 @@ class Mpich(AutotoolsPackage, mixins.FilterCompilerWrappers):
     provides('mpi@:3.0', when='@3:')
     provides('mpi@:1.3', when='@1:')
 
+    filter_compiler_wrappers('mpicc', 'mpicxx', 'mpif77', 'mpif90')
+
     # fix MPI_Barrier segmentation fault
     # see https://lists.mpich.org/pipermail/discuss/2016-May/004764.html
     # and https://lists.mpich.org/pipermail/discuss/2016-June/004768.html
@@ -169,12 +171,3 @@ def configure_args(self):
         config_args.append(device_config)
 
         return config_args
-
-    @property
-    def to_be_filtered_for_wrappers(self):
-        return [
-            join_path(self.prefix.bin, 'mpicc'),
-            join_path(self.prefix.bin, 'mpicxx'),
-            join_path(self.prefix.bin, 'mpif77'),
-            join_path(self.prefix.bin, 'mpif90')
-        ]