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/casync/casync.mk

@@ -0,0 +1,64 @@
+################################################################################
+#
+# casync
+#
+################################################################################
+
+CASYNC_VERSION = 4ad9bcb94bc83ff36cfc65515107ea06a88c2dfc
+CASYNC_SITE = $(call github,systemd,casync,$(CASYNC_VERSION))
+CASYNC_LICENSE = LGPL-2.1+
+CASYNC_LICENSE_FILES = LICENSE.LGPL2.1
+CASYNC_DEPENDENCIES = acl libcurl openssl
+
+CASYNC_CONF_OPTS = -Dman=false -Doss-fuzz=false -Dllvm-fuzz=false
+
+ifeq ($(BR2_PACKAGE_BASH_COMPLETION),y)
+CASYNC_DEPENDENCIES += bash-completion
+# The default path is correct, leave it as-is
+else
+CASYNC_CONF_OPTS += -Dbashcompletiondir=no
+endif
+
+ifeq ($(BR2_PACKAGE_LIBFUSE),y)
+CASYNC_DEPENDENCIES += libfuse
+CASYNC_CONF_OPTS += -Dfuse=true
+else
+CASYNC_CONF_OPTS += -Dfuse=false
+endif
+
+ifeq ($(BR2_PACKAGE_LIBSELINUX),y)
+CASYNC_DEPENDENCIES += libselinux
+CASYNC_CONF_OPTS += -Dselinux=true
+else
+CASYNC_CONF_OPTS += -Dselinux=false
+endif
+
+ifeq ($(BR2_PACKAGE_HAS_UDEV),y)
+CASYNC_DEPENDENCIES += udev
+CASYNC_CONF_OPTS += -Dudev=true
+else
+CASYNC_CONF_OPTS += -Dudev=false
+endif
+
+ifeq ($(BR2_PACKAGE_LIBZSTD),y)
+CASYNC_DEPENDENCIES += libzstd
+CASYNC_CONF_OPTS += -Dlibzstd=enabled
+else
+CASYNC_CONF_OPTS += -Dlibzstd=disabled
+endif
+
+ifeq ($(BR2_PACKAGE_XZ),y)
+CASYNC_DEPENDENCIES += xz
+CASYNC_CONF_OPTS += -Dliblzma=enabled
+else
+CASYNC_CONF_OPTS += -Dliblzma=disabled
+endif
+
+ifeq ($(BR2_PACKAGE_ZLIB),y)
+CASYNC_DEPENDENCIES += zlib
+CASYNC_CONF_OPTS += -Dlibz=enabled
+else
+CASYNC_CONF_OPTS += -Dlibz=disabled
+endif
+
+$(eval $(meson-package))