Remove unnecessary NULL checks in expr.c

The first is unnecessary because after_expand() never returns NULL, and the 'rest' pointer has been
dereferenced multiple times anyway.

The second is unnecessary because parse_number(&ptr) cannot set ptr to NULL.

source/expr.c

@@ -1703,7 +1703,6 @@ register unsigned char	c;
 			TruncateAndQuote(buffer, val, length, quote_em, pad_char);
 			new_free(&val);
 			new_free(&sub_buffer);
-			if (rest)
 			*rest = c2;
 			return rest;
 		}
@@ -1789,7 +1788,7 @@ register unsigned char	c;
 
 			    TruncateAndQuote(buffer, tmp2, length, quote_em, pad_char);
 			    new_free(&tmp2);
-			    return (ptr ? ptr : empty_string);
+			    return ptr;
 			}
 
 			/*