Bump Buildroot to 2021.02-rc3 (#1260)

* Rebase patches to Buildroot 2021.02-rc3

* Update Buildroot to 2021.02-rc3

* Declare Kernel headers to be Linux version 5.10 (since they are, and new Buildroot knows about 5.10)

buildroot/package/qt5/qt5mqtt/Config.in

@@ -0,0 +1,13 @@
+config BR2_PACKAGE_QT5MQTT
+	bool "qt5mqtt"
+	help
+	  Qt is a cross-platform application and UI framework for
+	  developers using C++.
+
+	  The Qt MQTT module provides a standard compliant
+	  implementation of the MQTT protocol specification. It
+	  enables applications to act as telemetry displays and
+	  devices to publish telemetry data.  The supported versions
+	  are MQTT 3.1, MQTT 3.1.1, and MQTT 5.0.
+
+	  https://doc.qt.io/QtMQTT/index.html

buildroot/package/qt5/qt5mqtt/qt5mqtt.hash

@@ -0,0 +1,6 @@
+# Hash locally calculated
+sha256  38f2bc1bcbdf76d30d78c86426c85f62a6c2091c997cad4b087039f795b2b406  qt5mqtt-5.15.2-br1.tar.gz
+
+# Hashes for license files:
+sha256  8ceb4b9ee5adedde47b31e975c1d90c73ad27b6b165a1dcd80c7c545eb65b903  LICENSE.GPL3
+sha256  0dbe024961f6ab5c52689cbd036c977975d0d0f6a67ff97762d96cb819dd5652  LICENSE.GPL3-EXCEPT

buildroot/package/qt5/qt5mqtt/qt5mqtt.mk

@@ -0,0 +1,15 @@
+################################################################################
+#
+# qt5mqtt
+#
+################################################################################
+
+QT5MQTT_VERSION = $(QT5_VERSION)
+QT5MQTT_SITE = https://code.qt.io/cgit/qt/qtmqtt.git
+QT5MQTT_SITE_METHOD = git
+QT5MQTT_INSTALL_STAGING = YES
+QT5MQTT_LICENSE = GPL-3.0 with exception
+QT5MQTT_LICENSE_FILES = LICENSE.GPL3 LICENSE.GPL3-EXCEPT
+QT5MQTT_SYNC_QT_HEADERS = YES
+
+$(eval $(qmake-package))