Prefer other types to int in extract.c

Prefer other types to int in extract.c

* src/extract.c (fd_chmod, extract_chdir, open_output_file)
(extract_file, extract_link, extract_symlink, extract_node)
(extract_fifo, tar_extractor_t, pepare_to_extract): Prefer char to
int for typeflag, since it’s a char.  All uses changed.
(fd_chmod): Use clearer code for errno.
(extract_dir, extract_file, create_placeholder_file, extract_link)
(extract_symlink, extract_node, extract_fifo, tar_extractor_t):
Return bool true for success, false for failure.  All uses changed.
(open_output_file): Prefer bool for boolean.
(prepare_to_extract): Simplify by returning the extractor a null
pointer, rather than storing through a pointer to an extractor.