caca-sharp: support systems with .dylib or .sl shared libraries.

csharp/caca-sharp.dll.config.in

@@ -1,3 +1,5 @@
 <configuration>
     <dllmap dll="libcaca.dll" target="libcaca.so.@LT_MAJOR@" />
+    <dllmap dll="libcaca.dll" target="libcaca.dylib.@LT_MAJOR@" />
+    <dllmap dll="libcaca.dll" target="libcaca.sl.@LT_MAJOR@" />
 </configuration>