[nre] Use VMM_NORETURN instead of NORETURN.
[nre] Removed linker-script dependency.
Use decltype() instead of typeof().

typeof() is a GCC extension, while decltype is in the C++11 standard.
Merge pull request #32 from Nils-TUD/nre-fixes

Changes to make Seoul usable from NRE again.
Properly round up page count in unsafe map mode. See #35.