readme: use string_list instead of space deliminations

Now this is possible in cgitrc -

readme=:README.md
readme=:readme.md
readme=:README.mkd
readme=:readme.mkd
readme=:README.rst
readme=:readme.rst
readme=:README.html
readme=:readme.html
readme=:README.htm
readme=:readme.htm
readme=:README.txt
readme=:readme.txt
readme=:README
readme=:readme
readme=:INSTALL.txt
readme=:install.txt
readme=:INSTALL
readme=:install

Suggested-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
diff --git a/ui-blob.h b/ui-blob.h
index ce3649f..16847b2 100644
--- a/ui-blob.h
+++ b/ui-blob.h
@@ -1,8 +1,8 @@
 #ifndef UI_BLOB_H
 #define UI_BLOB_H
 
-extern int cgit_ref_path_exists(const char *path, const char *ref);
-extern int cgit_print_file(char *path, const char *head);
-extern void cgit_print_blob(const char *hex, char *path, const char *head);
+extern int cgit_ref_path_exists(const char *path, const char *ref, int file_only);
+extern int cgit_print_file(char *path, const char *head, int file_only);
+extern void cgit_print_blob(const char *hex, char *path, const char *head, int file_only);
 
 #endif /* UI_BLOB_H */