Add cross-compilation support in the python Makefile and setup.py since
python has no such support.

The main point here is to first build a python interpreter to run on the
host, and then use it to compile the target python.

We also remove some error-generating code that is irrelevant in our
situation, such as checking if we can import a cross-compiled module.

Patch ported to python2.7 by Maxime Ripard <ripard@archos.com>

diff -rduNp Python-2.7.orig/Makefile.pre.in Python-2.7/Makefile.pre.in
--- Python-2.7.orig/Makefile.pre.in	2010-04-12 02:10:46.000000000 +0200
+++ Python-2.7/Makefile.pre.in	2010-09-21 16:46:07.000000000 +0200
@@ -404,8 +404,8 @@ platform: $(BUILDPYTHON)
 # Build the shared modules
 sharedmods: $(BUILDPYTHON)
 	@case $$MAKEFLAGS in \
-	*s*) $(RUNSHARED) CC='$(CC)' LDSHARED='$(BLDSHARED)' LDFLAGS='$(LDFLAGS)' OPT='$(OPT)' ./$(BUILDPYTHON) -E $(srcdir)/setup.py -q build;; \
-	*) $(RUNSHARED) CC='$(CC)' LDSHARED='$(BLDSHARED)' LDFLAGS='$(LDFLAGS)' OPT='$(OPT)' ./$(BUILDPYTHON) -E $(srcdir)/setup.py build;; \
+	*s*) $(RUNSHARED) CC='$(CC)' LDSHARED='$(BLDSHARED)' LDFLAGS='$(LDFLAGS)' OPT='$(OPT)' $(HOSTPYTHON) -E $(srcdir)/setup.py -q build;; \
+	*) $(RUNSHARED) CC='$(CC)' LDSHARED='$(BLDSHARED)' LDFLAGS='$(LDFLAGS)' OPT='$(OPT)' $(HOSTPYTHON) -E $(srcdir)/setup.py build;; \
 	esac
 
 # Build static library
@@ -538,7 +538,7 @@ Modules/python.o: $(srcdir)/Modules/pyth
 
 $(GRAMMAR_H) $(GRAMMAR_C): $(PGEN) $(GRAMMAR_INPUT)
 		-@$(INSTALL) -d Include
-		-$(PGEN) $(GRAMMAR_INPUT) $(GRAMMAR_H) $(GRAMMAR_C)
+		-$(HOSTPGEN) $(GRAMMAR_INPUT) $(GRAMMAR_H) $(GRAMMAR_C)
 
 $(PGEN):	$(PGENOBJS)
 		$(CC) $(OPT) $(LDFLAGS) $(PGENOBJS) $(LIBS) -o $(PGEN)
@@ -920,25 +920,25 @@ libinstall:	build_all $(srcdir)/Lib/$(PL
 	done
 	$(INSTALL_DATA) $(srcdir)/LICENSE $(DESTDIR)$(LIBDEST)/LICENSE.txt
 	PYTHONPATH=$(DESTDIR)$(LIBDEST)  $(RUNSHARED) \
-		./$(BUILDPYTHON) -Wi -tt $(DESTDIR)$(LIBDEST)/compileall.py \
+		$(HOSTPYTHON) -Wi -tt $(DESTDIR)$(LIBDEST)/compileall.py \
 		-d $(LIBDEST) -f \
 		-x 'bad_coding|badsyntax|site-packages|lib2to3/tests/data' \
 		$(DESTDIR)$(LIBDEST)
 	PYTHONPATH=$(DESTDIR)$(LIBDEST) $(RUNSHARED) \
-		./$(BUILDPYTHON) -Wi -tt -O $(DESTDIR)$(LIBDEST)/compileall.py \
+		$(HOSTPYTHON) -Wi -tt -O $(DESTDIR)$(LIBDEST)/compileall.py \
 		-d $(LIBDEST) -f \
 		-x 'bad_coding|badsyntax|site-packages|lib2to3/tests/data' \
 		$(DESTDIR)$(LIBDEST)
 	-PYTHONPATH=$(DESTDIR)$(LIBDEST)  $(RUNSHARED) \
-		./$(BUILDPYTHON) -Wi -t $(DESTDIR)$(LIBDEST)/compileall.py \
+		$(HOSTPYTHON) -Wi -t $(DESTDIR)$(LIBDEST)/compileall.py \
 		-d $(LIBDEST)/site-packages -f \
 		-x badsyntax $(DESTDIR)$(LIBDEST)/site-packages
 	-PYTHONPATH=$(DESTDIR)$(LIBDEST) $(RUNSHARED) \
-		./$(BUILDPYTHON) -Wi -t -O $(DESTDIR)$(LIBDEST)/compileall.py \
+		$(HOSTPYTHON) -Wi -t -O $(DESTDIR)$(LIBDEST)/compileall.py \
 		-d $(LIBDEST)/site-packages -f \
 		-x badsyntax $(DESTDIR)$(LIBDEST)/site-packages
 	-PYTHONPATH=$(DESTDIR)$(LIBDEST) $(RUNSHARED) \
-		./$(BUILDPYTHON) -Wi -t -c "import lib2to3.pygram, lib2to3.patcomp;lib2to3.patcomp.PatternCompiler()"
+		$(HOSTPYTHON) -Wi -t -c "import lib2to3.pygram, lib2to3.patcomp;lib2to3.patcomp.PatternCompiler()"
 
 # Create the PLATDIR source directory, if one wasn't distributed..
 $(srcdir)/Lib/$(PLATDIR):
@@ -1043,7 +1043,7 @@ libainstall:	all python-config
 # Install the dynamically loadable modules
 # This goes into $(exec_prefix)
 sharedinstall:
-	$(RUNSHARED) ./$(BUILDPYTHON) -E $(srcdir)/setup.py install \
+	$(RUNSHARED) $(HOSTPYTHON) -E $(srcdir)/setup.py install \
 	   	--prefix=$(prefix) \
 		--install-scripts=$(BINDIR) \
 		--install-platlib=$(DESTSHARED) \
diff -rduNp Python-2.7.orig/setup.py Python-2.7/setup.py
--- Python-2.7.orig/setup.py	2010-06-27 14:36:16.000000000 +0200
+++ Python-2.7/setup.py	2010-09-21 16:59:59.000000000 +0200
@@ -310,9 +310,9 @@ class PyBuildExt(build_ext):
         try:
             imp.load_dynamic(ext.name, ext_filename)
         except ImportError, why:
-            self.failed.append(ext.name)
-            self.announce('*** WARNING: renaming "%s" since importing it'
-                          ' failed: %s' % (ext.name, why), level=3)
+            self.announce('*** WARNING: Importing "%s" failed, probably '
+                          'because of cross-compilation' % ext.name, level=3)
+            return
             assert not self.inplace
             basename, tail = os.path.splitext(ext_filename)
             newname = basename + "_failed" + tail
@@ -346,10 +346,6 @@ class PyBuildExt(build_ext):
         return sys.platform
 
     def detect_modules(self):
-        # Ensure that /usr/local is always used
-        add_dir_to_list(self.compiler.library_dirs, '/usr/local/lib')
-        add_dir_to_list(self.compiler.include_dirs, '/usr/local/include')
-
         # Add paths specified in the environment variables LDFLAGS and
         # CPPFLAGS for header and library files.
         # We must get the values from the Makefile and not the environment
@@ -384,12 +380,6 @@ class PyBuildExt(build_ext):
                     for directory in reversed(options.dirs):
                         add_dir_to_list(dir_list, directory)
 
-        if os.path.normpath(sys.prefix) != '/usr':
-            add_dir_to_list(self.compiler.library_dirs,
-                            sysconfig.get_config_var("LIBDIR"))
-            add_dir_to_list(self.compiler.include_dirs,
-                            sysconfig.get_config_var("INCLUDEDIR"))
-
         try:
             have_unicode = unicode
         except NameError: