initial buildroot for linux 5.15

package/libcoap/Config.in

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+config BR2_PACKAGE_LIBCOAP
+	bool "libcoap"
+	help
+	  libcoap is a C implementation of a lightweight
+	  application-protocol for devices that are constrained their
+	  resources such as computing power, RF range, memory, bandwith,
+	  or network packet sizes. This protocol, CoAP, is standardized
+	  by the IETF as RFC 7252. For further information related to
+	  CoAP, see <http://coap.technology>.
+
+	  https://github.com/obgm/libcoap

package/libcoap/libcoap.hash

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+# Locally calculated
+sha256  29a0394a265d3febee41e5e2dc03d34292a0aede37f5f80334e529ac0dab2321  libcoap-4.2.1.tar.gz
+sha256  09dd86a017bad210527085008cbf706609c58210897b69845af14099577e7eb7  COPYING
+sha256  c51e85271aca3fbdd79bb4ee45dcfd854724538dad83b70afbbdfc62415e3e7f  LICENSE

package/libcoap/libcoap.mk

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+################################################################################
+#
+# libcoap
+#
+################################################################################
+
+LIBCOAP_VERSION = 4.2.1
+LIBCOAP_SITE = $(call github,obgm,libcoap,v$(LIBCOAP_VERSION))
+LIBCOAP_INSTALL_STAGING = YES
+LIBCOAP_LICENSE = BSD-2-Clause
+LIBCOAP_LICENSE_FILES = COPYING LICENSE
+LIBCOAP_DEPENDENCIES = host-pkgconf
+LIBCOAP_CONF_OPTS = --disable-examples --without-tinydtls
+LIBCOAP_AUTORECONF = YES
+
+ifeq ($(BR2_PACKAGE_GNUTLS),y)
+LIBCOAP_DEPENDENCIES += gnutls
+LIBCOAP_CONF_OPTS += --enable-dtls --with-gnutls --without-openssl
+else ifeq ($(BR2_PACKAGE_OPENSSL),y)
+LIBCOAP_DEPENDENCIES += openssl
+LIBCOAP_CONF_OPTS += --enable-dtls --without-gnutls --with-openssl
+else
+LIBCOAP_CONF_OPTS += --disable-dtls
+endif
+
+$(eval $(autotools-package))