Merge branch 'kb/fast-hashmap'

Improvements to our hash table to get it to meet the needs of the
msysgit fscache project, with some nice performance improvements.

* kb/fast-hashmap:
name-hash: retire unused index_name_exists()
hashmap.h: use 'unsigned int' for hash-codes everywhere
test-hashmap.c: drop unnecessary #includes
.gitignore: test-hashmap is a generated file
read-cache.c: fix memory leaks caused by removed cache entries
builtin/update-index.c: cleanup update_one
fix 'git update-index --verbose --again' output
remove old hash.[ch] implementation
name-hash.c: remove cache entries instead of marking them CE_UNHASHED
name-hash.c: use new hash map implementation for cache entries
name-hash.c: remove unreferenced directory entries
name-hash.c: use new hash map implementation for directories
diffcore-rename.c: use new hash map implementation
diffcore-rename.c: simplify finding exact renames
diffcore-rename.c: move code around to prepare for the next patch
buitin/describe.c: use new hash map implementation
add a hashtable implementation that supports O(1) removal
submodule: don't access the .gitmodules cache entry after removing it

diff --cc .gitignore
Simple merge

diff --cc Makefile
Simple merge

diff --cc builtin/describe.c
index 7db43dae1be95e86c21249d9150fc8553c367527,104202898e42f8c59cdd15a6433c4bef187d8493..dadd999c41f6aebe488d057e94e239dfb7dffaec
--- 1/builtin/describe.c
--- 2/builtin/describe.c
+++ b/builtin/describe.c
@@@ -6,10 -6,10 +6,10 @@@
  #include "exec_cmd.h"
  #include "parse-options.h"
  #include "diff.h"
- #include "hash.h"
+ #include "hashmap.h"
  #include "argv-array.h"
  
 -#define SEEN          (1u<<0)
 +#define SEEN          (1u << 0)
  #define MAX_TAGS      (FLAG_BITS - 1)
  
  static const char * const describe_usage[] = {
@@@ -36,8 -36,9 +36,8 @@@ static const char *diff_index_args[] = 
        "diff-index", "--quiet", "HEAD", "--", NULL
  };
  
 -
  struct commit_name {
-       struct commit_name *next;
+       struct hashmap_entry entry;
        unsigned char peeled[20];
        struct tag *tag;
        unsigned prio:2; /* annotated tag = 2, tag = 1, head = 0 */

diff --cc cache.h
Simple merge

diff --cc submodule.c
Simple merge

diff --cc unpack-trees.c
Simple merge