Fix building of GNUTLS and update to latest 2.x version.
* patches/gnutls-2.12.21/01-openssl-wincrypt.patch: New. * Makefile.am: Add patch. * src/Makefile.am (gpg4win_pkg_gnutls_configure): Force building with libgcrypt. Disable pkcs11 module. (LTLIBTASN1): (gpg4win_pkg_gnutls_make_args): Add hack to allow building latest version.
gnutls 2.12.21 does not seem to be well tested with Windows. At least
not with w64-mingw32. This is a minimal fix which is not guarnteed to
always work.