In sysconfig.parse_config_h(), the variables in pyconfig.h that have a commented-out '#undef' line are set to 0.  Fortunately, there is no Android API level 0.

Checking '== 0' ensures that autoreconf has been run to add '#undef ANDROID_API_LEVEL' to pyconfig.h.in. If this autoreconf step were to be missed, the test would (correctly) fail on the buildbots that are not Android as get_config_var() would return None then and the test would not be skipped and fail.

Most of the tests in the Python test suite do check 'not sysconfig.get_config_var()' instead, except:
    Lib/test/test_cmath.py|543 col 22| @unittest.skipIf(sysconfig.get_config_var('TANH_PRESERVES_ZERO_SIGN') == 0, "system tanh() function doesn't copy the sign")
    Lib/test/test_math.py|978 col 22| @unittest.skipIf(sysconfig.get_config_var('TANH_PRESERVES_ZERO_SIGN') == 0, "system tanh() function doesn't copy the sign")