or1k: Update core support in newlib and document

Extend the functionality of the support library in newlib:

 * Add or1k_interrupts_enable, or1k_interrupts_disable and
   or1k_interrupts_restore. Those functions handle the IEE flag in the
   status register.

 * Add the ability to re-configure the timer mode.

 * Add the ability to re-configure the timer handler. Currently only a
   tick counter is integrated by calling init. Keep this behavior for
   compatibility, but it is now possible to set own timer handlers,
   e.g., for scheduling etc.

 * The timer period can be re-configured now.

 * The timer initialization returns an int now which is -1 when the
   timer is not present. This does not break current implementations
   as it returns an int instead of nothing before.

 * Enabling the timer now also involves configuring the pre-set timer
   mode.

 * or1k_timer_disable now returns the TEE flag before the function was
   called. Together with the new or1k_timer_restore it therefore
   simplefies the implementation of atomic sections.

 * or1k_timer_pause pauses the counter. It can be continued by calling
   or1k_timer_enable.

Furthermore the whole support header is documented with doxygen. The
doxygen configuration is also part of this patch. Generate the
documentation in doc/ by running doxygen or1k-support.doxy.
or1k: Add malloc lock to newlib

As malloc may be called during software runtime or during an
exception, it is necessary to lock the access. In single core
environments it is sufficient to disable all interrupts during the
execution of malloc. This patch does this. The implementation also
keeps track of the current lock holder and allows recursion. Actually
both the exception and the software will never try to lock the malloc
while it is locked by the other one, as they are locked out during the
entire duration of the first call to __malloc_lock until the end of
the last call to __malloc_unlock. But this is the generic
implementation that eases extension to multicore.
or1k: Boards in libgloss

 * Adds two functions to a board implementation: _board_init and
   _board_init_early. _board_init is called after the C library is
   initialized before main is called, _board_init_early is called in
   the very beginning before anything happened (not even stack!).

 * Call functions from _start(crt0.S)

 * Empty board templates

 * README.boards for instructions of how to add a new board

Changelog: 2014-05-10  Stefan Wallentowitz  <stefan.wallentowitz@tum.de>
	    * or1k/crt0.S: Add board initialization function calls
	    * or1k/atlys.S: Empty implementation of board initialization functions
	    * or1k/de0_nano.S: ditto
	    * or1k/ml501.S: ditto
	    * or1k/or1ksim-uart.S: ditto
	    * or1k/or1ksim.S: ditto
	    * or1k/ordb1a3pe1500.S: ditto
	    * or1k/ordb2a.S: ditto
	    * or1k/orpsocrefdesign.S: ditto
	    * or1k/board_tmpl.c: New file, C board template
	    * or1k/board_tmpl.S: New file, assembly board template
	    * or1k/README.board: New file, add new board description
or1k: Code formatting and documentation in crt0.S

Follow up on the pull request discussion, this patch:

 * replaces 4 space identation with tabs, tabs for structuring

 * unifies the coding (spaces after commas, ..)

 * documents the coding guideline for this file as it is a rather
   sensible one

 * completes the main part documentation