CLEANUP: Fix typos in the http subsystem

Fix typos in code comment of the http subsystem.
diff --git a/src/http_conv.c b/src/http_conv.c
index 42a7616..c6cfdab 100644
--- a/src/http_conv.c
+++ b/src/http_conv.c
@@ -218,7 +218,7 @@
 {
 	int len;
 
-	/* If the constant flag is set or if not size is avalaible at
+	/* If the constant flag is set or if not size is available at
 	 * the end of the buffer, copy the string in other buffer
 	  * before decoding.
 	 */