cross-compilation support for python build

Lib/test/regrtest.py

 #! /usr/bin/env python3
 
 """
 Usage:
 
 python -m test [options] [test_name1 [test_name2 ...]]
 python path/to/Lib/test/regrtest.py [options] [test_name1 [test_name2 ...]]
 
 
 If no arguments or options are provided, finds all files matching
@@ skipping 1763 matching lines @@
         """
 
         assert self.isvalid()
         return self.expected
 
 def _make_temp_dir_for_build(TEMPDIR):
     # When tests are run from the Python build directory, it is best practice
     # to keep the test files in a subfolder.  It eases the cleanup of leftover
     # files using command "make distclean".
     if sysconfig.is_python_build():
-        TEMPDIR = os.path.join(sysconfig.get_config_var('srcdir'), 'build')
-        TEMPDIR = os.path.abspath(TEMPDIR)
+        TEMPDIR = os.path.abspath('build')
         try:
             os.mkdir(TEMPDIR)
         except FileExistsError:
             pass
 
     # Define a writable temp dir that will be used as cwd while running
     # the tests. The name of the dir includes the pid to allow parallel
     # testing (see the -j option).
     TESTCWD = 'test_python_{}'.format(os.getpid())
 
@@ skipping 23 matching lines @@
     assert __file__ == os.path.abspath(sys.argv[0])
 
     TEMPDIR, TESTCWD = _make_temp_dir_for_build(TEMPDIR)
 
     # Run the tests in a context manager that temporary changes the CWD to a
     # temporary and writable directory. If it's not possible to create or
     # change the CWD, the original CWD will be used. The original CWD is
     # available from support.SAVEDCWD.
     with support.temp_cwd(TESTCWD, quiet=True):
         main()