_gnutls_x509_get_dn() always return a null terminated string
use the original DER/BER data when verifying an OCSP response

Conflicts:
	lib/x509/ocsp.c
deinitialize the OCSP response der data

That also makes sure that reinitialization of ASN1 structures
are done when it is required only.
utilize the gnutls 3.2 functions
doc update
bumped version
released 3.2.21
guile: Build with warnings.

* guile/src/Makefile.am (AM_CFLAGS) [HAVE_GCC]: Add -Wall -Wextra
  -Wno-unused-parameter.
guile: Link with '-no-undefined'.

Fixes builds on MinGW.
Reported by Eli Zaretskii <eliz@gnu.org>.

* guile/src/Makefile.am (guile_gnutls_v_2_la_LDFLAGS): Add
  -no-undefined.
guile: Open binary file in binary mode, for the sake of MinGW.

Reported by Eli Zaretskii <eliz@gnu.org>.

* guile/tests/openpgp-keyring.scm: Use 'open-file' with "rb" instead of
  'open-input-file'.
Update 'NEWS'.