Changed the lvm-nm alias "-s" for -print-armap to "-M".

Changed the lvm-nm alias "-s" for -print-armap to "-M".
This will allow the "-s" flag to implemented in the future as it
is in darwin’s nm(1) to list symbols only in the specified section.

Given a LGTM by Shankar Easwaran who originally implemented
the support for lvm-nm’s -print-armap and archive map symbols.

llvm-svn: 212576