Force cast in sipEnumMemberDef

This resolves FTBFS due to a narrowing conversions using
C++11 dialect (GCC6) in python-tqt and python-trinity

Signed-off-by: Slávek Banko <slavek.banko@axis.cz>
(cherry picked from commit 0747f550f7)

sipgen/gencode.c

@@ -2737,6 +2737,9 @@ static int generateEnumMemberTable(sipSpec *pt, moduleDef *mod, classDef *cd,
         prcode(fp,
 "    {%N, ", emd->pyname);
 
+        // enums in sip are always int, but can be an unsigned in C++ code
+        // therefore it is necessary to force the cast in the generated files
+        prcode(fp, "(int)");
         if (cd != NULL)
         {
             if (isProtectedEnum(emd->ed))