Clean up some markup cruft.  A number of the macros that take no
parameters (like \UNIX) are commonly entered using an empty group to
separate the markup from a following inter-word space; this is not
needed when the next character is punctuation, or the markup is the
last thing in the enclosing group.  These cases were marked
inconsistently; the empty group is now *only* used when needed.
diff --git a/Doc/ext/unix.tex b/Doc/ext/unix.tex
index 7e6dfd2..396909e 100644
--- a/Doc/ext/unix.tex
+++ b/Doc/ext/unix.tex
@@ -13,7 +13,7 @@
 that reflects various system variables determined by configure when
 the Python interpreter was built, so people building module's don't
 have to resupply these settings.  This vastly simplifies the process
-of building extensions and custom interpreters on Unix systems.
+of building extensions and custom interpreters on \UNIX{} systems.
 
 The make file make file is distributed as the file
 \file{Misc/Makefile.pre.in} in the Python source distribution.  The