libseccomp: introduce BR2_PACKAGE_LIBSECCOMP_ARCH_SUPPORTS

Instead of duplicating the architecture dependency between the main
option and the Config.in comment, add a
BR2_PACKAGE_LIBSECCOMP_ARCH_SUPPORTS hidden option.

This is done in preparation to enabling libseccomp on ARM.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/libseccomp/Config.in

@@ -1,8 +1,13 @@
+config BR2_PACKAGE_LIBSECCOMP_ARCH_SUPPORTS
+	bool
+	default y if BR2_aarch64
+	default y if BR2_mips || BR2_mipsel || BR2_mips64 || BR2_mips64el
+	default y if BR2_i386 || BR2_x86_64
+	default y if BR2_powerpc64 || BR2_powerpc
+
 config BR2_PACKAGE_LIBSECCOMP
 	bool "libseccomp"
-	depends on BR2_aarch64 || BR2_mips || BR2_mipsel || BR2_mips64 || \
-		BR2_mips64el || BR2_i386 || BR2_x86_64 || BR2_powerpc64 || \
-		BR2_powerpc
+	depends on BR2_PACKAGE_LIBSECCOMP_ARCH_SUPPORTS
 	depends on BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_12
 	help
 	  High level interface to the Linux Kernel's seccomp filter
@@ -17,6 +22,5 @@ config BR2_PACKAGE_LIBSECCOMP
 	  https://github.com/seccomp/libseccomp
 
 comment "libseccomp needs a toolchain w/ headers >= 3.12"
-	depends on BR2_aarch64 || BR2_mips || BR2_mipsel || BR2_mips64 || \
-		BR2_mips64el || BR2_i386 || BR2_x86_64
+	depends on BR2_PACKAGE_LIBSECCOMP_ARCH_SUPPORTS
 	depends on !BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_12