Heavily inspired off linux kernel's dynamic debug:
* add a /sys/kernel/debug/dynamic_debug/control file
(accessible from linux side in /sys/class/mcos/mcos0/sys/kernel/debug/dynamic_debug/control)
* read from file to list debug statements (currently limited to 4k in size)
* write to file with '[file foo ][func bar ][line [x][-[y]]] [+-]p' to change values
Side effects:
* reindented all linker scripts, there is a new __verbose section
* added string function strpbrk
Change-Id: I36d7707274dcc3ecaf200075a31a2f0f76021059
