gadget-test: inherit arch dependencies from libaio

Fixes
http://autobuild.buildroot.org/results/7ad59020d4584a777d721352ae73ab2dd33326d7/build-end.log

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/gadgetfs-test/Config.in

@@ -6,8 +6,13 @@ config BR2_PACKAGE_GADGETFS_TEST
 
 config BR2_PACKAGE_GADGETFS_TEST_USE_AIO
 	bool "use asynchronous i/o"
-	depends on BR2_PACKAGE_GADGETFS_TEST
 	select BR2_PACKAGE_LIBAIO
+	depends on BR2_PACKAGE_GADGETFS_TEST
+	# libaio is available only on few architectures
+	depends on \
+		BR2_arm   || BR2_armeb || BR2_avr32  || BR2_i386    || \
+		BR2_m68k  || BR2_mips  || BR2_mipsel || BR2_powerpc || \
+		BR2_sparc || BR2_x86_64
 	help
 	  Select this to have gadgetfs-test do asynchronous I/O using
 	  the libaio library.