Fix the !HAVE_GETCWD_NULL code to behave more like the HAVE_GETCWD_NULL code. Include pathmax.h if not HAVE_GETCWD. Do not include xalloc.h. (INITIAL_BUFFER_SIZE): New symbol. Do not use xmalloc / xrealloc, since the caller is responsible for handling errors. Preserve errno around `free' during failure. Do not overrun buffer when using getwd.