Add fstrim support to restore NAND/eMMC write performance. 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

Change-Id: I0ba903cb7248b288152736f2e3392a5bdbe77ba3
update config (fstrim addition)

Change-Id: I5c872afbcd071d389d0db3f10862677c08212e2c
Build with -fno-strict-aliasing

Change-Id: I4117a526cdc93c96a9b7102727f5b33542810990
Signed-off-by: Evan McClain <aeroevan@gmail.com>
Busybox 1.21.0 squashed commit for jellybean

Change-Id: I423c7fc1254050c6495126b1b18dd33af07fed6b
Signed-off-by: Tanguy Pruvot <tanguy.pruvot@gmail.com>