CLEANUP: assorted typo fixes in the code and comments

This is 11th iteration of typo fixes
diff --git a/src/vars.c b/src/vars.c
index fd95eed..49937fe 100644
--- a/src/vars.c
+++ b/src/vars.c
@@ -189,7 +189,7 @@
 	_HA_ATOMIC_SUB(&var_global_size, size);
 }
 
-/* This function init a list of variabes. */
+/* This function init a list of variables. */
 void vars_init(struct vars *vars, enum vars_scope scope)
 {
 	LIST_INIT(&vars->head);