ELF unexec: Correct section header index

ELF unexec: Correct section header index

First a small fix.  The code incorrectly uses "NEW_SECTION_H (n)" when
it should have been using "NEW_SECTION_H (nn)" to find the name of the
section currently being processed.  Of course, before the bss
sections, n and nn have the same value, so this doesn't matter except
in the case of .sbss.  For .sbss this probably meant .bss (most likely
the next section) was copied from memory.  A later patch removes the
bogus .sbss handling anyway.

* unexelf.c (unexec): Use correct index to look up names.