coding-style: additional style for C code

coding-style: additional style for C code

To improve readability and to push more uniform code style.

Prefer 'if (false) {...}' for unused code so it get checked by the
compiler.
Define preferred indentation for 'switch' statement.
Require balanced brackets in 'if/else'.
Report the max line length.
Report the formatting strings for stdint/inttypes types.
Report the type 'target_addr_t'.
Prefer 'unsigned int' to 'unsigned'.

Change-Id: I0192a4ed298f6c6c432764fdd156cffd4b13fc89
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/6203
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Tested-by: jenkins
Reviewed-by: Oleksij Rempel <linux@rempel-privat.de>
Reviewed-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>
Reviewed-by: Marc Schink <dev@zapb.de>