Export "cache_name_compare()" helper function.

The "diff-tree" program needs it.

cache.h

@@ -105,5 +105,6 @@ extern char *sha1_to_hex(const unsigned char *sha1);	/* static buffer result! */
 
 /* General helper functions */
 extern void usage(const char *err);
+extern int cache_name_compare(const char *name1, int len1, const char *name2, int len2);
 
 #endif /* CACHE_H */

read-cache.c

@@ -245,7 +245,7 @@ int cache_match_stat(struct cache_entry *ce, struct stat *st)
 	return changed;
 }
 
-static int cache_name_compare(const char *name1, int len1, const char *name2, int len2)
+int cache_name_compare(const char *name1, int len1, const char *name2, int len2)
 {
 	int len = len1 < len2 ? len1 : len2;
 	int cmp;