usnic: remove SVN-style $Id$ tokens (and #idents)

This commit is also upstream in libfabric.
libfabric: various configury updates

1. Ensure to override CFLAGS properly.  Move the setting of CFLAGS outside the AM_CONDITIONAL so that Automake doesn't get confused (because CFLAGS is already set inside an AM_CONDITIONAL -- moving it outside the conditional ensure that this local CFLAGS override trumps all other CFLAGS overrides).
2. Only build libfabric on Linux. Add a little more configury to ensure that we only try to build libfabric on Linux.
3. Remove a dead/unused file
4. Fix typo in condition check
5. Use "false", not "/bin/false"
usnic: fix show_help message

Rename a few symbols to use libfabric-friendly names.  Fix a show_help
message when fi_av_insert times out.