'Expands variables references in ARCHS, and remove duplicates.'

def _ExpandArchs(self, archs, sdkroot):

    variable_mapping = self._VariableMapping(sdkroot)
    expanded_archs = []
    for arch in archs:
        if self.variable_pattern.match(arch):
            variable = arch
            try:
                variable_expansion = variable_mapping[variable]
                for arch in variable_expansion:
                    if (arch not in expanded_archs):
                        expanded_archs.append(arch)
            except KeyError as e:
                print ('Warning:    Ignoring    unsupported    variable    "%s".' % variable)
        elif (arch not in expanded_archs):
            expanded_archs.append(arch)
    return expanded_archs
