Fix Soprano 2.8.0 (and maybe earlier ones) build on OS X 10.8

soprano.osx10.8.diff

diff -ruN soprano-2.8.0.orig/soprano/vocabulary/rdf.cpp soprano-2.8.0/soprano/vocabulary/rdf.cpp
--- soprano-2.8.0.orig/soprano/vocabulary/rdf.cpp       2012-06-27 10:15:18.000000000 +0300
+++ soprano-2.8.0/soprano/vocabulary/rdf.cpp    2013-01-23 11:36:25.000000000 +0200
@@ -107,7 +107,7 @@
     return s_rdf()->rdf_first;
 }
 
-QUrl Soprano::Vocabulary::RDF::nil()
+QUrl Soprano::Vocabulary::RDF::nil_()
 {
     return s_rdf()->rdf_nil;
 }
diff -ruN soprano-2.8.0.orig/soprano/vocabulary/rdf.h soprano-2.8.0/soprano/vocabulary/rdf.h
--- soprano-2.8.0.orig/soprano/vocabulary/rdf.h 2012-06-27 10:15:18.000000000 +0300
+++ soprano-2.8.0/soprano/vocabulary/rdf.h      2013-01-23 11:36:38.000000000 +0200
@@ -94,7 +94,7 @@
              * The empty list, with no items in it. If the rest of a list is nil 
              * then the list has no more items in it. 
              */
-            SOPRANO_EXPORT QUrl nil();
+            SOPRANO_EXPORT QUrl nil_();
 
             /**
              * http://www.w3.org/1999/02/22-rdf-syntax-ns#object