CLEANUP: Fix spelling errors in comments

This is from the output of codespell. It's done at once over a bunch
of files and only affects comments, so there is nothing user-visible.
No backport needed.
diff --git a/src/http.c b/src/http.c
index d331699..8e38b0c 100644
--- a/src/http.c
+++ b/src/http.c
@@ -818,7 +818,7 @@
 				 * comparison is performed in two parts.
 				 */
 
-				/* This is the end, we dont have any other chunk. */
+				/* This is the end, we don't have any other chunk. */
 				if (bufs != chunks || !bufs[2])
 					return NULL;