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/dtterm/dtterm.msg

@@ -32,37 +32,37 @@ $ **  ----------------GENERAL LOCALIZATION NOTES SECTION END------------------
 $ *************************************<L>*************************************
 
 $ *****************************************************************************
-$
+$ 
 $ ***** NOTE FOR MESSAGE CATALOG TRANSLATORS *****
-$
+$ 
 $ There may be three types of messages in this file:
-$
+$ 
 $ 1. Messages that appear in dialogs or are displayed to the user.
-$
+$ 
 $     These messages are the default and they should ALL BE LOCALIZED.
 $     Note that these messages do NOT have any identification (see the
 $     comments for type 2 and 3 below).
-$
+$ 
 $ 2. Messages that only appear in the DT error log file ($HOME?.dt/errorlog).
-$
+$ 
 $     The localization of these messages is OPTIONAL.  These messages are
 $     identified by the following:
-$
+$ 
 $     MESSAGES xx-yy WILL ONLY APPEAR IN THE DT ERRORLOG FILE
-$
+$ 
 $ 3. Messages that should not be localized.
-$
+$ 
 $     These messages are identified by the following:
-$
+$ 
 $     DO NOT TRANSLATE or CHANGE or LOCALIZE MESSAGES xx-yy
-$
+$ 
 $ ***** END (NOTE FOR MESSAGE CATALOG TRANSLATORS) *****
-$
+$ 
 $ ********** PROLOGUE ****************
 $  Date    Name               Note
 $ ======== =================  ===============================================
 $ 03/15/94 B. May             Initial rev
-$
+$ 
 $ *****************************************************************************
 
 $set 1
@@ -164,9 +164,9 @@ $ These are the user-visible labels in the Global Options dialog box.
 $ #1 is the title. 
 $ The rest are resource types and values - look at the dialog box and 
 $ documentation for full specs. 
-$
+$ 
 $ DO NOT TRANSLATE MESSAGE 15
-$
+$ 
 2 OK
 3 Cancel
 4 Help