Fix apparently longstanding FORM OBJECT! bug

Forming of an object would print the object line by line, each with a
newline, and then remove the last character in the mold buffer to get
rid of the last newline.  There was no accounting for if nothing had
been added.

It's strange that this was in the 12-Dec-2012 open source release and
it hadn't been a (known) problem yet...seems like it would be common:

https://github.com/rebol/rebol/blob/25033f897b2bd466068d7663563cd3ff64740b94/src/core/s-mold.c#L880

src/core/s-mold.c

@@ -854,6 +854,7 @@ static void Form_Object(const REBVAL *value, REB_MOLD *mold)
 	REBVAL *keys = BLK_HEAD(keylist);
 	REBVAL *vals  = VAL_OBJ_VALUES(value); // first value is context
 	REBCNT n;
+	REBFLG had_output = FALSE;
 
 	// Prevent endless mold loop:
 	if (Find_Same_Block(MOLD_LOOP, value) > 0) {
@@ -864,10 +865,16 @@ static void Form_Object(const REBVAL *value, REB_MOLD *mold)
 
 	// Mold all words and their values:
 	for (n = 1; n < SERIES_TAIL(keylist); n++) {
-		if (!VAL_GET_EXT(keys + n, EXT_WORD_HIDE))
+		if (!VAL_GET_EXT(keys + n, EXT_WORD_HIDE)) {
+			had_output = TRUE;
 			Emit(mold, "N: V\n", VAL_TYPESET_SYM(keys + n), vals + n);
+		}
 	}
-	Remove_Sequence_Last(mold->series);
+
+	// Remove the final newline...but only if WE added something to the buffer
+	if (had_output)
+		Remove_Sequence_Last(mold->series);
+
 	Remove_Array_Last(MOLD_LOOP);
 }