[Bug 35964] New: gdip_format_string can segfault if format is NULL

http://bugs.winehq.org/show_bug.cgi?id=35964

Bug ID: 35964
           Summary: gdip_format_string can segfault if format is NULL
           Product: Wine
           Version: 1.7.16
          Hardware: x86
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: gdiplus
          Assignee: [e-mail]
          Reporter: [e-mail]

Created attachment 48062
  --> http://bugs.winehq.org/attachment.cgi?id=48062
patch to fix the issue

The parameter format to gdip_format_string can be NULL, but at one point its
attr member is checked without checking it is non-NULL, causing a segfault.
Patch attached.