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.

m4/.gitignore

@@ -180,6 +180,4 @@
 /obstack-printf.m4
 /extern-inline.m4
 /non-recursive-gnulib-prefix-hack.m4
-/getdelim.m4
-/getline.m4
 /inline.m4