Merge branch 'sp/stream-clean-filter'

When running a required clean filter, we do not have to mmap the
original before feeding the filter.  Instead, stream the file
contents directly to the filter and process its output.

* sp/stream-clean-filter:
  sha1_file: don't convert off_t to size_t too early to avoid potential die()
  convert: stream from fd to required clean filter to reduce used address space
  copy_fd(): do not close the input file descriptor
  mmap_limit: introduce GIT_MMAP_LIMIT to allow testing expected mmap size
  memory_limit: use git_env_ulong() to parse GIT_ALLOC_LIMIT
  config.c: add git_env_ulong() to parse environment variable
  convert: drop arguments other than 'path' from would_convert_to_git()

lockfile.c

@@ -224,8 +224,11 @@ int hold_lock_file_for_append(struct lock_file *lk, const char *path, int flags)
 	} else if (copy_fd(orig_fd, fd)) {
 		if (flags & LOCK_DIE_ON_ERROR)
 			exit(128);
+		close(orig_fd);
 		close(fd);
 		return -1;
+	} else {
+		close(orig_fd);
 	}
 	return fd;
 }