Convert hashtable usage over to khash

This updates khash.h with some extra features (like error checking
on allocations, ability to use wrapped malloc, foreach calls, etc),
creates two high-level wrappers around khash: `git_khash_str` and
`git_khash_oid` for string-to-void-ptr and oid-to-void-ptr tables,
then converts all of the old usage of `git_hashtable` over to use
these new hashtables.

For `git_khash_str`, I've tried to create a set of macros that
yield an API not too unlike the old `git_hashtable` API.  Since
the oid hashtable is only used in one file, I haven't bother to
set up all those macros and just use the khash APIs directly for
now.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/refs.h b/src/refs.h
index e4a225ca3..39648e6d9 100644
--- a/src/refs.h
+++ b/src/refs.h
@@ -10,7 +10,7 @@
 #include "common.h"
 #include "git2/oid.h"
 #include "git2/refs.h"
-#include "hashtable.h"
+#include "khash_str.h"
 
 #define GIT_REFS_DIR "refs/"
 #define GIT_REFS_HEADS_DIR GIT_REFS_DIR "heads/"
@@ -46,7 +46,7 @@ struct git_reference {
 };
 
 typedef struct {
-	git_hashtable *packfile;
+	git_khash_str *packfile;
 	time_t packfile_time;
 } git_refcache;