Log Message:
Update softhsm2 to version 2.6.1.

Pkgsrc changes:
 * Change dependency from botan to botan-devel to get version 2.x.

Upstream changes:

SoftHSM 2.6.1 - 2020-04-29

* Issue #542: Support Ed448/X448 for OpenSSL
* Issue #538: Improved warning and compilation issues for GCC10
* Issue #527: Fixed compilation issues for MacOS 10.15.4/Xcode 11.4

SoftHSM 2.6.0 - 2020-03-17

* Issue #493: Upgrade to Botan 2.
* Issue #530: Update appveyor build.
* Issue #438: Detect crypto algorithms by default.
  (Patch from Alon Bar-Lev)
* Issue #455: Provide a new configuration option to allow enabling and
  disabling various mechanisms (slots.mechanisms in the softhsm2.conf).
  (Thanks to Jakub Jelen)
* Issue #479: Increase SQLite busy timeout from 15 seconds to 3 minutes.
  (Patch from Jan Luebbe)
* Issue #513: Add configuration option to reset state on fork closing all
  sessions rather than keeping all sessions open in duplicate process.
  (Thanks to Anderson Toshiyuki Sasaki)
* Issue #500: C_WaitForSlotEvent implementation.
  (Patch from massey101)
* Issue #445: Add wrap support with CKM_AES_CBC.

Bugfixes:
* Issue #418: Set fields to NULL to avoid double free.
  (Patch from Brian J Murray)
* Issue #423: ENGINE_load_rdrand is not supported with older openssl.
  (Patch from Alon Bar-Lev)
* Issue #429: Updated prerequisite to build from repository.
  (Patch from Dharmesh Khandelwal)
* Issue #434: Fix build issues with CMake.
  (Patch from Peter Wu)
* Issue #435: Fix botan build without EDDSA.
  (Patch from Peter Wu)
* Issue #442: Release resources from OSSLEVPSymmetricAlgorithm.
  (Patch from Petr Menšík)
* Issue #449/#502: Do not copy zero sized buffer avoid null pointer reference.
  (Patch from space88man)
* Issue #464: Race condition with multiple threads closing last session and
  opening a newer sessions.
  (Patch from Takarth)
* Issue #452: Fixes to automake build fir undefined macros.
* Issue #462: User PIN count wrongly calculated.
  (Patch from Ondrej Hlavaty)
* Issue #516: Fix memory leak in OSSLCryptoFactory.
  (Patch from Anderson Sasaki)
* Issue #494: Allow null pointers as arguments when count is zero.
  (Patch from Yunjong Jeong)
* Issue #518: Sporadic problem in closing sessions because of lookup of
  object without prior locking.
* Issue #506: Check key type for C_EncryptInit and C_DecryptInit.
  (Patch from Yunjong Jeong)
* Issue #526: Adjust EDDSA code to return valid EC_PARAMS.
  (Patch from Jakub Jelen)
* Issue #452: Autogen failure on undefined macro AC_MSG_ERROR.
* Issue #527: Fixed some build errors for GCC 10.
* Issue #470: Null pointer arguments validation for C_EncryptFinal, etc.