Add support for C-style enums in C mode. And tests.

In backward compatible mode C style enums binding are correctly
generated

Examples/test-suite/lua/enums_runme.lua

@@ -19,4 +19,12 @@ assert(enums.globalinstance3==30)
 assert(enums.AnonEnum1==0)
 assert(enums.AnonEnum2==100)
 
+-- In C enums from struct are exported without prefixing with struct name
+-- In C++ they are prefixed.
+-- We are emulating xor :)
+assert(enums.BAR1 ~= enums.Foo_BAR1) -- It is either C style, or C++ style, but not both
+assert((enums.BAR1 ~= nil ) or (enums.Foo_BAR1 ~= nil))
+
+assert(enums.Phoo ~= enums.iFoo_Phoo)
+assert((enums.Phoo == 50) or (enums.iFoo_Phoo == 50))
 -- no point in checking fns, C will allow any value