add py_builddir macro

debian/changelog

+python-defaults (2.6.6-14) UNRELEASED; urgency=low
+
+  * python.mk: add py_builddir macro.
+    $(call py_builddir, 2.6) returns "build/lib.linux-x86_64-2.6" on amd64
+
+ -- Piotr Ożarowski <piotr@debian.org>  Sun, 27 Mar 2011 16:29:05 +0200
+
 python-defaults (2.6.6-13) experimental; urgency=low
 
   * Add python2.7 as a supported Python version.

debian/python.mk

@@ -39,3 +39,6 @@ py_libdir_sh = $$(_py_=$(strip $(1)); python$${_py_\#python*} -c 'from distutils
 
 # Arguments to pass to setup.py install
 py_setup_install_args = --install-layout=deb
+
+# distutils' build directory
+py_builddir = $(shell python$(strip $(1)) -c "from distutils.command.build import build; from distutils.core import Distribution; b = build(Distribution()); b.finalize_options(); print(b.build_platlib)")