Ensure macros and parameters with the same name are not repeated.

This covers the case when a macro is set with the same name as a
parameter. Previously, the macro would be repeated on the command line,
which causes certain toolchains to break (ex. IAR assembler). Now the
config system will override the parameter's value with the macro's
value.

tools/config/__init__.py

@@ -1092,17 +1092,37 @@ class Config(object):
                                       "' doesn't have a value")
 
     @staticmethod
-    def parameters_to_macros(params):
+    def _parameters_and_config_macros_to_macros(params, macros):
-        """ Encode the configuration parameters as C macro definitions.
+        """ Return the macro definitions generated for a dictionary of
+        ConfigParameters and a dictionary of ConfigMacros (as returned by
+        get_config_data). The ConfigMacros override any matching macros set by
+        the ConfigParameters.
 
         Positional arguments:
         params - a dictionary mapping a name to a ConfigParameter
+        macros - a dictionary mapping a name to a ConfigMacro
 
-        Return: a list of strings that encode the configuration parameters as
+        Return: a list of strings that are the C pre-processor macros
-        C pre-processor macros
         """
-        return ['%s=%s' % (m.macro_name, m.value) for m in params.values()
+        all_macros = {
-                if m.value is not None]
+            p.macro_name: p.value for p in params.values() if p.value is not None
+        }
+
+        config_macros = {
+            m.macro_name: m.macro_value for m in macros.values()
+        }
+
+        all_macros.update(config_macros)
+        macro_list = []
+        for name, value in all_macros.items():
+            # If the macro does not have a value, just append the name.
+            # Otherwise, append the macro as NAME=VALUE
+            if value is None:
+                macro_list.append(name)
+            else:
+                macro_list.append("%s=%s" % (name, value))
+
+        return macro_list
 
     @staticmethod
     def config_macros_to_macros(macros):
@@ -1126,8 +1146,7 @@ class Config(object):
         """
         params, macros = config[0], config[1]
         Config._check_required_parameters(params)
-        return Config.config_macros_to_macros(macros) + \
+        return Config._parameters_and_config_macros_to_macros(params, macros)
-            Config.parameters_to_macros(params)
 
     def get_config_data_macros(self):
         """ Convert a Config object to a list of C macros