build: Fix compatibility with Python 3

Change-Id: I6e38315945a683a87bbeb4b4a352de3c7122ef7c
Refs: #3493

.waf-tools/doxygen.py

@@ -85,7 +85,7 @@ class doxygen(Task.Task):
 
 			# Override with any parameters passed to the task generator
 			if getattr(self.generator, 'pars', None):
-				for k, v in self.generator.pars.iteritems():
+				for k, v in self.generator.pars.items():
 					self.pars[k] = v
 
 			self.doxy_inputs = getattr(self, 'doxy_inputs', [])