message catalogs: fix comment lines, also remove linux hack in merge.c

According to the spec, blank lines in message catalogs or lines
beginning with '$ ' are valid comments.

However, there were many cases where lines in the message catalogs
contained just a single '$', without the required space after it.

Under linux, this caused 126766 error lines (in my builds) of the
form:

... unknown directive `': line ignored

This also causes gencat to exit with a non-0 exit code.  Even though
gencat says it ignores the line, it really doesn't.

An early porting change to programs/localized/util/merge.c was made to
ignore this return value on linux.  This hack has now been removed.

Build logs are a lot smaller and cleaner now.

cde/programs/localized/it_IT.ISO8859-1/msg/MotifApp.msg

@@ -1,10 +1,10 @@
-$
+$ 
 $ +SNOTICE
-$
+$ 
 $  $XConsortium: MotifApp.msg /main/5 1996/10/19 16:10:42 rws $
-$
+$ 
 $  RESTRICTED CONFIDENTIAL INFORMATION:
-$
+$ 
 $  The information in this document is subject to special
 $  restrictions in a confidential disclosure agreement between
 $  HP, IBM, Sun, USL, SCO and Univel.  Do not distribute this
@@ -12,11 +12,11 @@ $  document outside HP, IBM, Sun, USL, SCO, or Univel without
 $  Sun's specific written approval.  This document and all copies
 $  and derivative works thereof must be returned or destroyed at
 $  Sun's request.
-$
+$ 
 $  Copyright 1993 Sun Microsystems, Inc.  All rights reserved.
-$
+$ 
 $ +ENOTICE
-$
+$ 
 
 $quote "