Replace direct accesses to sched_active_thread and sched_active_pid with
the helper functions thread_getpid() and thread_get_active(). This serves
two purposes:
1. It makes accidental writes to those variable from outside core less likely.
2. Casting off the volatile qualifier is now well contained to those two
functions
- Removed stdio_init() from newlib's _init(), as this is too late in the boot
process to allow DEBUG()ing during periph_init()
- Added stdio_init() to the various cpu_init() routines of the ARM CPUs just
before periph_init()
Replaces the special heap command approach of the lpc_common module with a more general heap command approach. Module lpc_common was already removed with PR #2118. PR #2118 integrated cpu/lpc_common code in cpu/lpc2387. With PR #3530 special heap handling for cpu/lpc2387 was replaced by newlib memory management which uses _sbrk_r to allocate chunks from the heap. _sbrk_r uses _sheap and _eheap symbols that are defined in lpc2387.ld and can be used together with mallinfo function for heap statistics.
Add small stubs for _times_r and _link_r so that code using times()
or link() can still compile. The functions are marked as not implemented
and return invalid codes.
