Fix psql tab-completion for identifiers containing dollars.

Dollar ($) is a legit character for identifiers, except as the first
character, since commit 1bd22f55cf in version 7.4. Update the
tab-completion code accordingly.

Author: Mikhail Gribkov
Reviewed-by: Vik Fearing
Discussion: https://www.postgresql.org/message-id/CAMEv5_sTAvPvhye%2Bu4jkWDe5UGDiQ1ZkQomnKCboM08zDzOe%3Dg%40mail.gmail.com

src/bin/psql/tab-complete.c

@@ -76,7 +76,7 @@
 #endif
 
 /* word break characters */
-#define WORD_BREAKS		"\t\n@$><=;|&{() "
+#define WORD_BREAKS		"\t\n@><=;|&{() "
 
 /*
  * Since readline doesn't let us pass any state through to the tab completion
@@ -6061,7 +6061,7 @@ identifier_needs_quotes(const char *ident)
 	/* Check syntax. */
 	if (!((ident[0] >= 'a' && ident[0] <= 'z') || ident[0] == '_'))
 		return true;
-	if (strspn(ident, "abcdefghijklmnopqrstuvwxyz0123456789_") != strlen(ident))
+	if (strspn(ident, "abcdefghijklmnopqrstuvwxyz0123456789_$") != strlen(ident))
 		return true;
 
 	/*