Share hash table test structs

This saves several words in the hash table object at the cost of an
indirection at runtime.  This seems to be a gain in overall
performance.

FIXME: We cache hash test objects in a rather clumsy way. A better
solution is sought.

* src/lisp.h (struct Lisp_Hash_Table): Use a pointer to the test
struct.  All references adapted.
* src/alloc.c (garbage_collect):
* src/fns.c (struct hash_table_user_test, hash_table_user_tests)
(mark_fns, get_hash_table_user_test): New state for caching test
structs, and functions managing it.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/pgtkterm.c b/src/pgtkterm.c
index 57ea82daa5e..b731f52983d 100644
--- a/src/pgtkterm.c
+++ b/src/pgtkterm.c
@@ -7178,7 +7178,7 @@ If set to a non-float value, there will be no wait at all.  */);
 
   DEFVAR_LISP ("pgtk-keysym-table", Vpgtk_keysym_table,
     doc: /* Hash table of character codes indexed by X keysym codes.  */);
-  Vpgtk_keysym_table = make_hash_table (hashtest_eql, 900, Weak_None, false);
+  Vpgtk_keysym_table = make_hash_table (&hashtest_eql, 900, Weak_None, false);
 
   window_being_scrolled = Qnil;
   staticpro (&window_being_scrolled);