fstrim: New applet

fstrim applet is a port from util-linux.

"Trimming" your NAND/eMMC storage will restore the write performance
back to normal after having slow down issues on sequential write and
random write due to usage over time.

Good reading on subject:
http://forum.xda-developers.com/showthread.php?t=1971852

(with long options and CLEAN_UP turned on)
function                                             old     new   delta
.rodata                                           148494  148791    +297
fstrim_main                                            -     283    +283
fstrim_sfx                                             -     128    +128
packed_usage                                       28826   28903     +77
applet_main                                         2760    2768      +8
applet_names                                        2343    2350      +7
applet_nameofs                                       690     692      +2
------------------------------------------------------------------------------
(add/remove: 3/0 grow/shrink: 5/0 up/down: 802/0)             Total: 802 bytes

Signed-off-by: Malek Degachi <malek-degachi@laposte.net>
Cc: Eugene San (eugenesan) <eugenesan@gmail.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>