Implement PathGetShortPathA/W and change its prototype to match the
documentation on MSDN.

diff --git a/include/shlobj.h b/include/shlobj.h
index 4cbafd1..f626a58 100644
--- a/include/shlobj.h
+++ b/include/shlobj.h
@@ -841,6 +841,11 @@
 DECL_WINELIB_TYPE_AW(FILEGROUPDESCRIPTOR)
 DECL_WINELIB_TYPE_AW(LPFILEGROUPDESCRIPTOR)
 
+/****************************************************************************
+ * Path Manipulation Routines
+ */
+VOID WINAPI PathGetShortPath(LPWSTR pszPath);
+
 #include <poppack.h>
 
 /*****************************************************************************