employ new explicit "exists in index?" API

Each caller of index_name_exists() knows whether it is looking for a
directory or a file, and can avoid the unnecessary indirection of
index_name_exists() by instead calling index_dir_exists() or
index_file_exists() directly.

Invoking the appropriate search function explicitly will allow a
subsequent patch to relieve callers of the artificial burden of having
to add a trailing '/' to the pathname given to index_dir_exists().

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/read-cache.c b/read-cache.c
index 885943a..b8d3759 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -643,7 +643,7 @@
 			if (*ptr == '/') {
 				struct cache_entry *foundce;
 				++ptr;
-				foundce = index_name_exists(istate, ce->name, ptr - ce->name, ignore_case);
+				foundce = index_dir_exists(istate, ce->name, ptr - ce->name);
 				if (foundce) {
 					memcpy((void *)startPtr, foundce->name + (startPtr - ce->name), ptr - startPtr);
 					startPtr = ptr;
@@ -652,7 +652,7 @@
 		}
 	}
 
-	alias = index_name_exists(istate, ce->name, ce_namelen(ce), ignore_case);
+	alias = index_file_exists(istate, ce->name, ce_namelen(ce), ignore_case);
 	if (alias && !ce_stage(alias) && !ie_match_stat(istate, alias, st, ce_option)) {
 		/* Nothing changed, really */
 		free(ce);