kernel: add rt_critical_level that return the lock count of scheduler

Out side world may be interested in whether the scheduler is locked or
not. Provide an API to tell that.
kernel: let rt_thread_idle_excute loop until there is no dead thread

Out side world is difficult to tell whethere there is dead thread
remaining. If rt_thread_idle_excute only do one cleanup, it's hard to
finish cleanups outside the idle thread. So let is loop and do all the
cleanups in one call.
TC: print a summary after all the tests
TC: format code, expand TABs

No functional changes.
DFS: let mount fail on device open error
Merge pull request #217 from grissiom/fix-dfs

DFS: let mount fail on device open error
Merge pull request #214 from grissiom/rtt-next2

Rtt next2
Merge pull request #216 from grissiom/more-tc

More tc
TC: more tolerate on the timeout tick in semaphore_dynamic

With system that has RT_TICK_PER_SECOND is 1000, it's easy to get one
tick error.
TC: expand TABs
TC: more tolerate for tick in TC thread
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.