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/app-defaults/Dtpad.tmsg

@@ -34,20 +34,20 @@ $set 1
 15 "F3"
 
 16 "<Key>F3:"
-$
+$ 
 $ Message 17 is the geometry of the dtpad editor.  The Default is 80x24
 $  characters.  In locale's which have multibyte chars, this is too big
 $  and should probably changed to 40x24.
-$
+$ 
 17 80x24
 
-$
+$ 
 $ Messages 18 - 35 are Post CDE/SI new messages.  They replace 1 - 16.
-$
+$ 
 $ ----------------------------------------------------------------------------
 $ Menu Accelerators
 $ ----------------------------------------------------------------------------
-$
+$ 
 $ Messages 18 20 22 24 26 28 30 32 34 can be translated. These are shown on 
 $ the menu.  Messages 19 21 23 25 27 29 31 33 35 should not be changed 
 $ unless accelerator keys need to be changed in your language. If you want 
@@ -56,14 +56,14 @@ $ text to use the same letter.  One occasion to have different accelerator
 $ text and accelerator key is for multibyte languages in which it may be 
 $ undesirable for the accelerator key to require use of an input method.
 $ Example; (Change underlined part only)
-$
+$ 
 $  Menu label: "Keyword..." --> "Abcdef..."
-$
+$ 
 $  1 Ctrl+K       -->  1 Ctrl+A
 $         -                   -
 $  2 Ctrl<Key>k   -->  2 Ctrl<Key>a
 $             -                   -
-$
+$ 
 $ ******** Message 18, 19. Menu label is "Print...".
 $ ******** 18 >> print.acceleratorText
 18 Ctrl+P
@@ -110,10 +110,10 @@ $ ******** 34 >> overstrike.acceleratorText
 $ ******** 35 >> overstrike.accelerator
 35 <Key>osfInsert
 
-$
+$ 
 $ Messages 36 and 37 specify the fonts to be used in the renderTables
 $  for the printing output.  Message 36 is used by the headers and footers.
 $  Message 37 is used by the text portion.
-$
+$ 
 36 -dt-application-bold-r-normal-serif-0-120-0-0-m-0-*-*
 37 -dt-application-medium-r-normal-serif-0-100-0-0-m-0-*-*