Significant changes in or1k libgloss and newlib

Summary:
 * Adds an extra exception stack to support virtual memory in baremetal (people may want to use this)
 * Reentrancy differentiates between exceptions and software itself
 * Dynamic reentrancy as enablement for multicore (to be merged later)
 * Add board initialization
 * Add restore functions for exceptions and timer, disable returns corresponding value now
 * Timer is more generic now
 * Cleanup and documentation