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/C/app-defaults/Dthelpview.tmsg

@@ -34,7 +34,7 @@ $                              40 for multi-byte
 $ Dthelpview*man_text.columns = 20 for single-byte
 $                               10 for multi-byte
 3 20
-$
+$ 
 $ Dthelpview*searchShell.searchForm.keyWord.columns = 30 for single-byte
 $                                                     15 for multi-byte
 4 30