daemon, generator: Use power of 2 for initial size of Hashtbl.create

Before 2011 it was recommended to use a prime number for the initial
size.  In 2011 the OCaml hash table was reimplemented using a hash
function based on Murmur 3.  Hashtbl.create now adjusts the initial
size to the next power of 2 (minimum 16).  So replace obsolete
'Hashtbl.create 13' with 'Hashtbl.create 16'.

Author: rwmjones

builder/builder.ml

@@ -46,7 +46,7 @@ let remove_duplicates index =
    * (name, arch) tuples, so it possible to ignore duplicates,
    * and versions with a lower revision.
    *)
-  let nseen = Hashtbl.create 13 in
+  let nseen = Hashtbl.create 16 in
   List.iter (
     fun (name, { Index.arch; revision }) ->
       let id = name, arch in

builder/index_parser.ml

@@ -55,7 +55,7 @@ let get_index ~downloader ~sigchecker ?(template = false)
         in
         n, (find_arch fields)
     ) sections in
-    let nseen = Hashtbl.create 13 in
+    let nseen = Hashtbl.create 16 in
     List.iter (
       fun (n, arch) ->
         let id = n, arch in
@@ -71,7 +71,7 @@ let get_index ~downloader ~sigchecker ?(template = false)
     (* Check for repeated fields. *)
     List.iter (
       fun (n, fields) ->
-        let fseen = Hashtbl.create 13 in
+        let fseen = Hashtbl.create 16 in
         List.iter (
           fun (field, subkey, _) ->
             let hashkey = (field, subkey) in

resize/resize.ml

@@ -630,7 +630,7 @@ read the man page virt-resize(1).
    * that the user has asked to be ignored or deleted.
    *)
   let find_partition =
-    let hash = Hashtbl.create 13 in
+    let hash = Hashtbl.create 16 in
     List.iter (fun ({ p_name = name } as p) -> Hashtbl.add hash name p)
       partitions;
     fun ~option name ->
@@ -881,7 +881,7 @@ read the man page virt-resize(1).
     surplus in
 
   (* Mark the --lv-expand LVs. *)
-  let hash = Hashtbl.create 13 in
+  let hash = Hashtbl.create 16 in
   List.iter (fun ({ lv_name = name } as lv) -> Hashtbl.add hash name lv) lvs;
 
   List.iter (