openblas: derives from MakefilePackage (#2488)

* MakefilePackage: changed build_args and install_args for consistency with #2464
openblas: derives from MakefilePackage

* MakefilePackage: changed default edit behavior

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

@@ -49,5 +49,6 @@ def edit(self, spec, prefix):
         if sys.platform == 'darwin':
             filter_file(r'^INSTALL=.*', 'INSTALL=install', makefile)
 
-    def install_args(self):
-        return ['prefix={0}'.format(prefix)]
+    @property
+    def install_targets(self):
+        return ['install', 'prefix={0}'.format(self.prefix)]