Bug 678332-GIO: Fix build on Windows/non-GCC

-gconverterinputstream.c: Avoid GCCism by not using non-standard pointer
 arithmetic on void*, but do a cast to char * as that seems to be what the
 variable was used for.
-gtestdbus.c: Don't include unistd.h unconditionally, and use g_usleep()
 instead of usleep(), as usleep() is not universally available.

gio/gconverterinputstream.c

@@ -415,7 +415,7 @@ read_internal (GInputStream *stream,
   buffer_read (&priv->converted_buffer, buffer, available);
 
   total_bytes_read = available;
-  buffer += available;
+  (char *) buffer += available;
   count -= available;
 
   /* If there is no data to convert, and no pre-converted data,

gio/gtestdbus.c

@@ -26,7 +26,9 @@
 
 #include <stdlib.h>
 #include <stdio.h>
+#ifdef HAVE_UNISTD_H
 #include <unistd.h>
+#endif
 
 #include <glib.h>
 
@@ -560,7 +562,7 @@ start_daemon (GTestDBus *self)
       g_spawn_command_line_async (command, NULL);
       g_free (command);
 
-      usleep (500 * 1000);
+      g_usleep (500 * 1000);
     }
 
   /* Cleanup */