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/dtpdmd/dtpdmd.msg

@@ -29,19 +29,19 @@ $ *****************************************************************************
 $set 1
 
 $    /* NL_COMMENT
-$
+$ 
 $	General Translator Comments
-$
+$ 
 $       - The acronyms "pdm" and "PDM" are used in several
 $         messages, and were derived from the english phrase
 $         "Print Dialog Manager". The acronyms should not be
 $         localized.
-$
+$ 
 $       - The acronym "pdmd" is used in several messages,
 $         and was derived from the english phrase "Print
 $         Dialog Manager Daemon". The acronym should not be
 $         localized.
-$
+$ 
 $     */
 1 usage: %1$s [options]\n\
 \n\
@@ -61,13 +61,13 @@ where [options] includes:\n\
 4 %s: error, cannot create Xt signal pipe\n
 
 $    /* NL_COMMENT
-$
+$ 
 $       - Do not translate the word "SelectionRequest" in
 $         messages 5, 6 and 7.
-$
+$ 
 $       - Do not translate the word "XmbTextPropertyToTestList"
 $         in message 7.
-$
+$ 
 $     */
 5 %s: error, unable to get SelectionRequest property\n
 6 %s: error, invalid format for SelectionRequest property\n
@@ -76,21 +76,21 @@ $     */
 8 %s: error, unable to create message pipe\n
 
 $    /* NL_COMMENT
-$
+$ 
 $       - Do not translate the word "fork" in message 9.
-$
+$ 
 $     */
 9 %s: error, unable to fork\n
 
 10 %1$s: error, cannot execute \"%2$s\" \n
 
 $    /* NL_COMMENT
-$
+$ 
 $       - Do not translate the word "exec" in message 11.
-$
+$ 
 $       - Do not translate the words "-display" or
 $         "-vdisplay" in message 11.
-$
+$ 
 $     */
 11 %1$s: exec message logged at %2$s\n\
    exec error message = \"%3$s\"\n\
@@ -108,12 +108,12 @@ message to the requesting client on behalf of\n\
 the PDM because of an XIO error\n
 
 $    /* NL_COMMENT
-$
+$ 
 $       - Do not translate the word "stderr" in message 14.
-$
+$ 
 $       - Do not translate the words "-display" or
 $         "-vdisplay" in message 14.
-$
+$ 
 $     */
 14 %1$s: pdm message logged at %2$s\n\
    pdm       = \"%3$s\"\n\