Update softkeymaster for BoringSSL.

* Disable an odd, 192-bit curve that BoringSSL no longer supports.
* Only set the "ASN.1 flag" when not using BoringSSL as it's the default
  now in BoringSSL.
* Use a non-deprecated function to free the thread's error queue.

Change-Id: I54a08724aef0344421fe9097e524d66550af0f81
Merge "Update softkeymaster for BoringSSL."