Make NSNetServices use formal protocol, as in 10.6. When compiling with clang, use @optional, otherwise fall back to defining an empty protocol and defining an informal protocol with the methods.

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@31594 72102866-910b-0410-8b05-ffd578937521

Source/NSNetServices.m

@@ -155,12 +155,12 @@ static Class concreteBrowserClass;
 }
 
 
-- (id) delegate
+- (id<NSNetServiceDelegate>) delegate
 {
   return _delegate;
 }
 
-- (void) setDelegate: (id) delegate
+- (void) setDelegate: (id<NSNetServiceDelegate>) delegate
 {
   _delegate = delegate;
 }
@@ -449,12 +449,12 @@ static Class concreteBrowserClass;
 }
 
 
-- (id) delegate
+- (id<NSNetServiceBrowserDelegate>) delegate
 {
   return _delegate;
 }
 
-- (void) setDelegate: (id) delegate
+- (void) setDelegate: (id<NSNetServiceBrowserDelegate>) delegate
 {
   _delegate = delegate;
 }