package/nginx: disallow AIO support on arc

The nginx AIO support cannot build on arc, because it hardcodes
the usage of SYS_eventfd(), while it should just use eventfd() from
the C library.

Fixes:
  http://autobuild.buildroot.org/results/f3e/f3e2c7a937517a5444f8c6cc0b02692af897b3e0/

[Thomas: adjust comment as suggested by Yann.]

Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/nginx/Config.in

@@ -17,9 +17,11 @@ if BR2_PACKAGE_NGINX
 config BR2_PACKAGE_NGINX_FILE_AIO
 	bool "file AIO support"
 	# Does not build, because nginx hardcodes using SYS_eventfd,
-	# but it's not available on AArch64, only eventfd() is.
-	# See https://bugs.launchpad.net/linaro-aarch64/+bug/1160013
+	# but it's available on neither AArch64 nor ARC where only
+	# eventfd() is available.  See
+	# https://bugs.launchpad.net/linaro-aarch64/+bug/1160013
 	depends on !BR2_aarch64
+	depends on !BR2_arc
 
 config BR2_PACKAGE_NGINX_HTTP
 	bool "http server"