CLEANUP: assorted typo fixes in the code and comments
This is 22nd iteration of typo fixes
diff --git a/src/fd.c b/src/fd.c
index f4a28cd..3387653 100644
--- a/src/fd.c
+++ b/src/fd.c
@@ -337,7 +337,7 @@
void fd_delete(int fd)
{
/* we must postpone removal of an FD that may currently be in use
- * by another thread. This can happend in the following two situations:
+ * by another thread. This can happen in the following two situations:
* - after a takeover, the owning thread closes the connection but
* the previous one just woke up from the poller and entered
* the FD handler iocb. That thread holds an entry in running_mask