boost: add BR2_PACKAGE_BOOST_CONTEXT_ARCH_SUPPORTS

Rework boost-context dependencies and manage them through the hidden
BR2_PACKAGE_BOOST_CONTEXT_ARCH_SUPPORTS

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/boost/Config.in

@@ -69,10 +69,18 @@ config BR2_PACKAGE_BOOST_CONTAINER
 # http://www.boost.org/doc/libs/1_59_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_i386
+	default y if BR2_mips
+	default y if BR2_mipsel
+	default y if BR2_powerpc
+	default y if BR2_x86_64
+
 config BR2_PACKAGE_BOOST_CONTEXT
 	bool "boost-context"
-	depends on ((BR2_arm || BR2_armeb) && BR2_ARM_CPU_HAS_ARM) || \
-		BR2_i386 || BR2_mips || BR2_mipsel || BR2_powerpc || BR2_x86_64
+	depends on BR2_PACKAGE_BOOST_CONTEXT_ARCH_SUPPORTS
 	depends on !BR2_TOOLCHAIN_HAS_GCC_BUG_64735
 	help
 	  C++11 context switching library.