fix memory leak in dfs_elm.c and umount fatfs when mount fatfs fails (this bug leads to mkfs failure in linux)

Add RT_MTD_ESRC definitions. If the source page has issue when copying a page, the low level can return this error code. 

libm is a frequently used lib. Newlib is compiled with
-ffunction-sections in recent GCC tool chains. The linker would just
link in the functions that have been referenced. So setting this won't
result in bigger text size.

Newlib already have optimized and full featured math implementation. To
use it, one should add:

    env['LIBS'] = ['m']

or equivalent to the SConstruct.

Declare sin/cos and M_PI in math.h.

remove product ID

add a dcd operation to send status in control transfer

elm fatfs support mkfs with no need to  run dfs_mount elm first; and can mount/umount/mkfs without reset any more

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2581 bbd45198-f89e-11dd-88c7-29a3b14d5316

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2580 bbd45198-f89e-11dd-88c7-29a3b14d5316

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2579 bbd45198-f89e-11dd-88c7-29a3b14d5316

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2578 bbd45198-f89e-11dd-88c7-29a3b14d5316

remove the drivers in uffs/nand which is already out of date. now you can look simulator to explore how to use uffs on nand flash or Realtouch demo code on github

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2576 bbd45198-f89e-11dd-88c7-29a3b14d5316

1. fix bug in uffs_nandif.c to work with mtd nand driver; 2)clean code in uffs_nandif.c and dfs_uffs.h

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2575 bbd45198-f89e-11dd-88c7-29a3b14d5316

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2572 bbd45198-f89e-11dd-88c7-29a3b14d5316

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2571 bbd45198-f89e-11dd-88c7-29a3b14d5316