cursor-sprite-xcursor: Use standard cursor names

The cursor name for META_CURSOR_POINTER was "hand" for both
the primary and legacy name lookups.

Many modern cursor themes (e.g. Bibata, Adwaita, Google Dot) don't
provide a cursor named "hand", causing XcursorLibraryLoadCursor
to fail.

This made the cursor disappear or Cinnamon crash when hovering URL
links in notifications.

Use "pointer" (the CSS3 cursor spec name) as the primary name
and "hand2" (the traditional X11 cursor) as the legacy fallback.

Both are universally available across cursor themes.

Fixes #801

The previous commit actually fixes the crash. This commit prevents it
from happening by using a better cursor name.

Author: clefebvre

src/backends/meta-cursor-sprite-xcursor.c

@@ -55,7 +55,7 @@ meta_cursor_get_name (MetaCursor cursor)
     case META_CURSOR_HELP:
       return "question_arrow";
     case META_CURSOR_POINTER:
-      return "hand";
+      return "pointer";
     case META_CURSOR_PROGRESS:
       return "left_ptr_watch";
     case META_CURSOR_WAIT:
@@ -141,7 +141,7 @@ meta_cursor_get_legacy_name (MetaCursor cursor)
     case META_CURSOR_HELP:
       return "question_arrow";
     case META_CURSOR_POINTER:
-      return "hand";
+      return "hand2";
     case META_CURSOR_PROGRESS:
       return "left_ptr_watch";
     case META_CURSOR_WAIT: