dfs: rename varialbe name in dfs_filesystem_lookup

empty is confused in dfs_filesystem_lookup.
dfs: fix dfs_unmount bug

fix #211
dfs: make elmfatfs check secter size everytime

more infomation:
http://www.rt-thread.org/phpBB3/topic2965.html
Merge pull request #215 from prife/master

fix dfs_unmount bug
Merge pull request #218 from grissiom/more-tc

More tc
Moved the configuration options to the SRC directory
Moved the configuration options to the SRC directory
ARMCC complier is usable.
Merge branch 'master' of https://github.com/RT-Thread/rt-thread
Merge branch 'master' into SQLite_on_ARMCC
Merge pull request #219 from geniusgogo/SQLite_on_ARMCC

Sq lite on armcc
TC: re-implement the loop feature

We should not use the _tc_stat to determine whether we should loop the
TCs. Use an other variable and introduce tc_loop FinSh command.
TC: delay longer in tc_stop