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/es_ES.ISO8859-1/msg/dtlp.msg

@@ -108,9 +108,9 @@ $  This is the label that appears in the title bar of the error dialog.
 
 160 "Información de impresión"
 
-$
+$ 
 $  -- Strings used in the Print dialog and Select Printer dialog in CDEnext --
-$
+$ 
 $  This is the label for the field indicating the file(s) that will be printed.
 170 "Nombres de archivo: "
 
@@ -124,9 +124,9 @@ $  This is the label for the printer list in the Select Printer dialog.
 $  This is the label for the text box in the Select Printer dialog.
 200 "Información acerca de la impresora:"
 
-$
+$ 
 $  -- The following are error messages added for CDEnext --
-$
+$ 
 $  File is not printable or does not exist.
 210 "Este archivo no se puede imprimir o no existe."