package/erlang: support build when gcc __atomic_* exist

While Erlang will use it's own atomic operations, it can also use gcc
__atomic_* builtins. This is now listed in Erlang's HOWTO/INSTALL.md.

This change was necessary on RISC-V, since Erlang didn't have a built-in
implementation, but it was able to use gcc's __atomic_* functions.

Signed-off-by: Frank Hunleth <fhunleth@troodon-software.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/erlang/Config.in

@@ -6,9 +6,11 @@ config BR2_PACKAGE_HOST_ERLANG_ARCH_SUPPORTS
 config BR2_PACKAGE_ERLANG_ARCH_SUPPORTS
 	bool
 	# see HOWTO/INSTALL.md for Erlang's supported platforms
-	# when using its native atomic ops implementation
+	# when using its native atomic ops implementation or gcc's
+	# __atomic_* builtins
 	default y if BR2_i386 || BR2_x86_64 || BR2_powerpc || \
-		BR2_sparc_v9 || BR2_arm || BR2_aarch64 || BR2_mipsel
+		BR2_sparc_v9 || BR2_arm || BR2_aarch64 || BR2_mipsel || \
+		BR2_TOOLCHAIN_HAS_ATOMIC
 	# erlang needs host-erlang
 	depends on BR2_PACKAGE_HOST_ERLANG_ARCH_SUPPORTS