Do not look at host headers/libraries in cross-compile mode

When we are cross-compiling, setup.py should never look in /usr or
/usr/local to find headers or libraries. A later patch adds a
mechanism to tell setup.py to look in a specific directory for headers
and libraries.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
---
 setup.py |   39 +++++++++++++++++++++------------------
 1 file changed, 21 insertions(+), 18 deletions(-)

Index: Python-2.7.2/setup.py
===================================================================
--- Python-2.7.2.orig/setup.py
+++ Python-2.7.2/setup.py
@@ -373,9 +373,10 @@
 
     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')
-        self.add_multiarch_paths()
+        if os.environ.get('CROSS_COMPILING') != 'yes':
+            add_dir_to_list(self.compiler.library_dirs, '/usr/local/lib')
+            add_dir_to_list(self.compiler.include_dirs, '/usr/local/include')
+            self.add_multiarch_paths()
 
         # Add paths specified in the environment variables LDFLAGS and
         # CPPFLAGS for header and library files.
@@ -383,10 +384,7 @@
         # directly since an inconsistently reproducible issue comes up where
         # the environment variable is not set even though the value were passed
         # into configure and stored in the Makefile (issue found on OS X 10.3).
-        for env_var, arg_name, dir_list in (
-                ('LDFLAGS', '-R', self.compiler.runtime_library_dirs),
-                ('LDFLAGS', '-L', self.compiler.library_dirs),
-                ('CPPFLAGS', '-I', self.compiler.include_dirs)):
+        for env_var, arg_name, dir_list in ():
             env_val = sysconfig.get_config_var(env_var)
             if env_val:
                 # To prevent optparse from raising an exception about any
@@ -411,17 +409,6 @@
                     for directory in reversed(options.dirs):
                         add_dir_to_list(dir_list, directory)
 
-        if os.path.normpath(sys.prefix) != '/usr' \
-                and not sysconfig.get_config_var('PYTHONFRAMEWORK'):
-            # OSX note: Don't add LIBDIR and INCLUDEDIR to building a framework
-            # (PYTHONFRAMEWORK is set) to avoid # linking problems when
-            # building a framework with different architectures than
-            # the one that is currently installed (issue #7473)
-            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:
@@ -430,11 +417,16 @@
         # lib_dirs and inc_dirs are used to search for files;
         # if a file is found in one of those directories, it can
         # be assumed that no additional -I,-L directives are needed.
-        lib_dirs = self.compiler.library_dirs + [
-            '/lib64', '/usr/lib64',
-            '/lib', '/usr/lib',
-            ]
-        inc_dirs = self.compiler.include_dirs + ['/usr/include']
+        lib_dirs = self.compiler.library_dirs
+        inc_dirs = self.compiler.include_dirs
+
+        if os.environ.get('CROSS_COMPILING') != 'yes':
+            lib_dirs += [
+                '/lib64', '/usr/lib64',
+                '/lib', '/usr/lib',
+                ]
+            inc_dirs += ['/usr/include']
+
         exts = []
         missing = []
 
@@ -867,6 +859,9 @@
             db_inc_paths.append('/pkg/db-3.%d/include' % x)
             db_inc_paths.append('/opt/db-3.%d/include' % x)
 
+        if os.environ.get('CROSS_COMPILING') == 'yes':
+            db_inc_paths = []
+
         # Add some common subdirectories for Sleepycat DB to the list,
         # based on the standard include directories. This way DB3/4 gets
         # picked up when it is installed in a non-standard prefix and
@@ -1019,6 +1014,9 @@
         MIN_SQLITE_VERSION = ".".join([str(x)
                                     for x in MIN_SQLITE_VERSION_NUMBER])
 
+        if os.environ.get('CROSS_COMPILING') == 'yes':
+            sqlite_inc_paths = []
+
         # Scan the default include directories before the SQLite specific
         # ones. This allows one to override the copy of sqlite on OSX,
         # where /usr/include contains an old version of sqlite.
@@ -1118,6 +1116,8 @@
         # the more recent berkeleydb's db.h file first in the include path
         # when attempting to compile and it will fail.
         f = "/usr/include/db.h"
+        if os.environ.get('CROSS_COMPILING') == 'yes':
+            f = ''
 
         if sys.platform == 'darwin':
             if is_macosx_sdk_path(f):