[auth] fix detection of root CAs on Linux (fixes #13640)

(cherry picked from commit 08ec25b and a6a2982)

Author: jef-n

src/core/auth/qgsauthcertutils.h

@@ -25,13 +25,13 @@
 #include "qgsauthconfig.h"
 
 #if QT_VERSION >= 0x050000
-#define SSL_ISSUER_INFO( var, prop ) var.issuerInfo( prop ).first()
+#define SSL_ISSUER_INFO( var, prop ) var.issuerInfo( prop ).value(0)
 #else
 #define SSL_ISSUER_INFO( var, prop ) var.issuerInfo( prop )
 #endif
 
 #if QT_VERSION >= 0x050000
-#define SSL_SUBJECT_INFO( var, prop ) var.subjectInfo( prop ).first()
+#define SSL_SUBJECT_INFO( var, prop ) var.subjectInfo( prop ).value(0)
 #else
 #define SSL_SUBJECT_INFO( var, prop ) var.subjectInfo( prop )
 #endif

src/core/auth/qgsauthmanager.cpp

@@ -2360,8 +2360,12 @@ bool QgsAuthManager::removeCertAuthority( const QSslCertificate& cert )
 
 const QList<QSslCertificate> QgsAuthManager::getSystemRootCAs()
 {
+#ifndef Q_OS_MAC
+  return QSslSocket::systemCaCertificates();
+#else
   QNetworkRequest req;
   return req.sslConfiguration().caCertificates();
+#endif
 }
 
 const QList<QSslCertificate> QgsAuthManager::getExtraFileCAs()