eturns a tuple (status, details), where 'status' is one of the following
    constants:

    - CONFIG_H_OK: all is well, go ahead and compile
    - CONFIG_H_NOTOK: doesn't look good
    - CONFIG_H_UNCERTAIN: not sure -- unable to read pyconfig.h

    'details' is a human-readable string explaining the situation.

    Note there are two ways to conclude "OK": either 'sys.version' contains
    the string "GCC" (implying that this Python was built with GCC), or the
    installed "pyconfig.h" contains the string "__GNUC__".
    r