Replace fwd decls in WillGetIfMatch with includes.

We need the definition of both classes in this header because
we call member functions from those classes here, but right
now we only have two forward declarations.
This patch replaces both forward declarations with the proper
includes to make the header compile on it's own.

FWCore/Framework/interface/WillGetIfMatch.h

@@ -11,14 +11,13 @@ See comments in the file GetterOfProducts.h.
 */
 
 #include <functional>
+#include "DataFormats/Provenance/interface/BranchDescription.h"
+#include "FWCore/Framework/interface/EDConsumerBase.h"
 #include "FWCore/Utilities/interface/InputTag.h"
 #include "FWCore/Utilities/interface/EDGetToken.h"
 
 namespace edm {
 
-  class BranchDescription;
-  class EDConsumerBase;
-
   template<typename T>
   class WillGetIfMatch {
   public: