oprofile: disable on xtensa

Missing memory barrier definition. Fixes
http://autobuild.buildroot.net/results/df7/df797a81111fa15de9337adefca05cbac156d0b2/.

Also, add nios2 to the dependencies comment while at it.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/oprofile/Config.in

@@ -6,6 +6,7 @@ config BR2_PACKAGE_OPROFILE
 	select BR2_PACKAGE_LIBPFM4 if BR2_powerpc
 	depends on BR2_INSTALL_LIBSTDCPP
 	depends on !BR2_aarch64 && !BR2_nios2 # binutils
+	depends on !BR2_xtensa
 	# libpfm4 is needed on PowerPC, and requires thread support
 	depends on BR2_TOOLCHAIN_HAS_THREADS || !BR2_powerpc
 	help
@@ -25,7 +26,8 @@ config BR2_PACKAGE_OPROFILE
 	  libraries, and applications.
 
 comment "oprofile needs a toolchain w/ C++"
-	depends on BR2_USE_MMU && !BR2_aarch64
+	depends on BR2_USE_MMU
+	depends on !BR2_aarch64 && !BR2_nios2 && !BR2_xtensa
 	depends on !BR2_INSTALL_LIBSTDCPP
 
 comment "oprofile needs a toolchain w/ threads on PPC"