libs: vendor qca (Qt Cryptographic Architecture, Qt6) for kf6-kwallet ksecretd

kf6-kwallet's ksecretd daemon (the org.freedesktop.secrets Secret Service
provider) requires Qca-qt6 2.3.1. Vendor QCA 2.3.10 under the full-fork model
and build the gcrypt provider plugin (backed by the vendored libgcrypt) so QCA
has a working SymmetricCipher/Hash/PBKDF2 backend on Redox. External-toolkit
providers (ossl/nss/botan/gnupg/pkcs11/cyrus-sasl) are disabled — those
libraries are not part of the Redox userland; logger + softstore (pure-Qt) are
kept.

Source edit: the top-level Qt6 find_package required the Test component
unconditionally; gate it on BUILD_TESTS so a tools/tests-off build configures
without Qt6Test. Install via DESTDIR since QCA anchors its install dirs to the
absolute Qt prefix (/usr), which ignores cmake --install --prefix.

Build libgpg-error + libgcrypt with --with-pic so their static archives can be
linked into the qca-gcrypt shared plugin. Add qca to kf6-kwallet deps.

local/recipes/libs/qca/source/examples/randomtest/randomtest.cpp

@@ -0,0 +1,72 @@
+/*
+ Copyright (C) 2004, 2006 Brad Hards <bradh@frogmouth.net>
+
+ Permission is hereby granted, free of charge, to any person obtaining a copy
+ of this software and associated documentation files (the "Software"), to deal
+ in the Software without restriction, including without limitation the rights
+ to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ copies of the Software, and to permit persons to whom the Software is
+ furnished to do so, subject to the following conditions:
+
+ The above copyright notice and this permission notice shall be included in
+ all copies or substantial portions of the Software.
+
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+ AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+// QtCrypto has the declarations for all of QCA
+#include <QtCrypto>
+
+#include <QCoreApplication>
+#include <QDebug>
+
+#include <iostream>
+
+#ifdef QT_STATICPLUGIN
+#include "import_plugins.h"
+#endif
+
+int main(int argc, char **argv)
+{
+    // the Initializer object sets things up, and
+    // also does cleanup when it goes out of scope
+    QCA::Initializer init;
+
+    QCoreApplication app(argc, argv);
+
+    qDebug() << "This example generates random numbers";
+
+    int randInt;
+    // This is the standard way to generate a random integer.
+    randInt = QCA::Random::randomInt();
+    qDebug() << "A random number: " << randInt;
+
+    // If you wanted a random character (octet), you could
+    // use something like:
+    unsigned char randChar;
+    randChar = QCA::Random::randomChar();
+    // It might not be printable, so this may not produce output
+    std::cout << "A random character: " << randChar << std::endl;
+
+    QCA::SecureArray tenBytes(10);
+    // If you need more random values, you may want to
+    // get an array, as shown below.
+    tenBytes = QCA::Random::randomArray(10);
+
+    // To make this viewable, we convert to hexadecimal.
+    std::cout << "A random 10 byte array (in hex): ";
+    std::cout << qPrintable(QCA::Hex().arrayToString(tenBytes)) << std::endl;
+
+    // Under some circumstances, you may want to create a
+    // Random object, rather than a static public member function.
+    // This isn't normally the easiest way, but it does work
+    QCA::Random myRandomObject;
+    randChar = myRandomObject.nextByte();
+    tenBytes = myRandomObject.nextBytes(10);
+    return 0;
+}