carets: properly display when no line feed is present

* src/location.c (location_caret): finish the line with one whether or not it
is present in input. Rewrite code without getline.
(cleanup_caret): Reset the caret_info global.
* bootstrap.conf: No longer require getline.

lib/.gitignore

@@ -267,8 +267,6 @@
 /xstrndup.h
 /binary-io.c
 /xsize.c
-/getdelim.c
-/getline.c
 /bitrotate.c
 /math.c
 /sig-handler.c