package/boost: enable context/coroutine for arm variants

Add boost context support for aarch64/aarch64_be.

Context support for ARM is only available in the AAPCS ABI, so switch to
AAPCS ABI for all ARM variants.

While we're at it, update the URL about the context architecture support
to the one corresponding to the current version of boost.

Signed-off-by: Pieter De Gendt <pieter.degendt@gmail.com>
[Arnout: update URL, extend commit message]
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

package/boost/Config.in

@@ -68,12 +68,13 @@ config BR2_PACKAGE_BOOST_CONTAINER
 	  Standard library containers and extensions.
 
 # see
-# http://www.boost.org/doc/libs/1_59_0/libs/context/doc/html/context/architectures.html
+# http://www.boost.org/doc/libs/1_78_0/libs/context/doc/html/context/architectures.html
 # for the list of supported architectures. Sparc pretends to be
 # supported, but it doesn't build.
 config BR2_PACKAGE_BOOST_CONTEXT_ARCH_SUPPORTS
 	bool
 	default y if ((BR2_arm || BR2_armeb) && BR2_ARM_CPU_HAS_ARM)
+	default y if (BR2_aarch64 || BR2_aarch64_be)
 	default y if BR2_i386
 	default y if BR2_mips
 	default y if BR2_mipsel

package/boost/boost.mk

@@ -85,7 +85,7 @@ HOST_BOOST_OPTS += --no-cmake-config toolset=gcc threading=multi \
 
 ifeq ($(BR2_MIPS_OABI32),y)
 BOOST_ABI = o32
-else ifeq ($(BR2_arm),y)
+else ifeq ($(BR2_arm)$(BR2_armeb)$(BR2_aarch64)$(BR2_aarch64_be),y)
 BOOST_ABI = aapcs
 else
 BOOST_ABI = sysv