Everywhere: Replace a bundle of dbg with dbgln.

These changes are arbitrarily divided into multiple commits to make it
easier to find potentially introduced bugs with git bisect.Everything:

The modifications in this commit were automatically made using the
following command:

    find . -name '*.cpp' -exec sed -i -E 's/dbg\(\) << ("[^"{]*");/dbgln\(\1\);/' {} \;

Services/WindowServer/main.cpp

@@ -113,7 +113,7 @@ int main(int, char**)
         return 1;
     }
 
-    dbg() << "Entering WindowServer main loop";
+    dbgln("Entering WindowServer main loop");
     loop.exec();
     ASSERT_NOT_REACHED();
 }