object-store: merge "object-store-ll.h" and "object-store.h"

The "object-store-ll.h" header has been introduced to keep transitive
header dependendcies and compile times at bay. Now that we have created
a new "object-store.c" file though we can easily move the last remaining
additional bit of "object-store.h", the `odb_path_map`, out of the
header.

Do so. As the "object-store.h" header is now equivalent to its low-level
alternative we drop the latter and inline it into the former.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

mailmap.c

@@ -6,7 +6,7 @@
 #include "string-list.h"
 #include "mailmap.h"
 #include "object-name.h"
-#include "object-store-ll.h"
+#include "object-store.h"
 #include "setup.h"
 
 char *git_mailmap_file;