Remove the check of PHP_OPENSSL inside SETUP_OPENSSL. It's the
responsibility of the caller to determine whether they want to
enable openssl or not. This makes SSL detection in IMAP work,
which uses a different option.

Additionally also clarify that --with-openssl-dir cannot actually
be used to specify an OpenSSL directory -- these options just
serve as a way to enable OpenSSL in extensions without also
enabling the OpenSSL extension. They need to be renamed to
something clearer in master.

Closes GH-5091.

SSL_CTX is a refcounted structure, which will be held by the SSL
handle, so we can free it here.

Normalization include:
- Use dnl for everything that can be ommitted when configure is built in
  favor of the shell comment character # which is visible in the output.
- Line length normalized to 80 columns
- Dots for most of the one line sentences
- Macro definitions include similar pattern header comments now

If the root directory was missing, an extra CWD without arguments was
made. Also, the MKD contained an empty string.

Now the CWD will use / and MKDs will be issued starting from the root
directory.