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/fr_FR.ISO8859-1/msg/dtcm.msg

@@ -1973,7 +1973,7 @@ $ 	The following message were added because message numbers from
 $    	IBM and Sunsoft conflicted - they both used the same message number
 $    	for different messages.  The IBM message number was changed as
 $    	follows:
-$
+$ 
 $		1100 was 978 from IBM
 $		1101 was 979 from IBM. 
 $		1102 was 981 from IBM. 
@@ -2038,12 +2038,12 @@ $ is the text displayed in that warning dialog; the %s will be replaced
 $ by the name of the font.
 1118	"Agenda : Avertissement - Imprimer"
 1119	"Avertissement - Impossible de charger la police %s."
-$
+$ 
 $ Message 1120 appears in an error dialog when an appointment cannot
 $   be scheduled.
 1120	"L'événement ne peut avoir lieu dans le temps donné.\nL'opération a été annulée."
 
-$
+$ 
 $ Message 1121 is placed in the title bar of a warning dialog if a
 $ print job fails because the Print Server returns BadAlloc.  Message
 $ 1122 is the text displayed in that warning dialog.