miscellaneous: clean up trailing whitespace throughout

The entire tree's polluted with inappropriate trailing
whitespace. This commit rids our environment of all of
those useless keystrokes. Unfortunately, it sure ain't
a permanent solution and requires every contributor to
instruct their editor(s) to prevent or eliminate them.

Plus it's strongly recommended we all insert something
like what's shown below to our '.gitconfig' file so as
to provide at least some warnings when we try to apply
any patches (git am) that do contain the #@!%& things!

References(s):
~/.gitconfig excerpt ---------------------------------
[core]
  whitespace = trailing-space, space-before-tab, blank-at-eof
[apply]
  whitespace = warn
--------------------------------- ~/.gitconfig excerpt

Signed-off-by: Jim Warner <james.warner@comcast.net>

include/nls.h

@@ -1,4 +1,4 @@
-/* 
+/*
  * This header was copied from util-linux at fall 2011.
  */
 

include/strutils.h

@@ -1,4 +1,4 @@
-/* 
+/*
  * This header was copied from util-linux at fall 2011.
  */
 

include/xalloc.h

@@ -1,4 +1,4 @@
-/* 
+/*
  * This header was copied from util-linux at fall 2011.
  */