End list when indent is not reached

Otherwise
```
- foo
- bar
+ baz
```
will become a nested list

1 files changed, 2 insertions, 0 deletions

diff --git a/smu.c b/smu.c
index e58bcd4..cc80ca2 100644
--- a/smu.c
+++ b/smu.c
@@ -391,6 +391,8 @@ dolist(const char *begin, const char *end, int newblock) {
 					else
 						break;
 				}
+				else if (j < indent)
+					run = 0;
 			}
 			ADDC(buffer, i) = *p;
 		}