Fix file_path_helper FPH_LOCAL_DIR_ENTRY.

Commit e5e4c54d changed "." to a constant, but the wrong one.
Should have been FPH_CHAR_DOT, not FPH_CHAR_PATH_SEPARATOR.

Change-Id: I041f6507947f1631f0af133bff0fa3270313391a
Reviewed-on: https://gerrit.libreoffice.org/5001Reviewed-by: Fridrich Strba <fridrich@documentfoundation.org>
Tested-by: Fridrich Strba <fridrich@documentfoundation.org>

sal/osl/unx/file_path_helper.cxx

@@ -40,7 +40,7 @@
   inline const rtl::OUString FPH_PATH_SEPARATOR()
       { return rtl::OUString(FPH_CHAR_PATH_SEPARATOR); }
   inline const rtl::OUString FPH_LOCAL_DIR_ENTRY()
-      { return rtl::OUString(FPH_CHAR_PATH_SEPARATOR); }
+      { return rtl::OUString(FPH_CHAR_DOT); }
   inline const rtl::OUString FPH_PARENT_DIR_ENTRY()
       { return rtl::OUString(".."); }