Valgrind works on PPC and AMD64 as well nowadays.

Use Kconfig to ensure valgrind can only be enabled on supported archs.

package/valgrind/Config.in

@@ -1,6 +1,7 @@
 config BR2_PACKAGE_VALGRIND
 	bool "valgrind"
 	default n
+	depends BR2_i386 || BR2_powerpc || BR2_x86_64
 	help
 	  Tool for debugging and profiling Linux programs.
 

package/valgrind/valgrind.mk

@@ -77,11 +77,7 @@ $(TARGET_DIR)/usr/bin/valgrind: $(VALGRIND_DIR)/none/vgskin_none.so
 	#cp $(VALGRIND_DIR)/woody.supp $(TARGET_DIR)/usr/lib/valgrind/
 	touch -c $(TARGET_DIR)/usr/bin/valgrind
 
-ifeq ($(BR2_i386),y)
 valgrind: $(TARGET_DIR)/usr/bin/valgrind
-else
-valgrind:
-endif
 
 valgrind-source: $(DL_DIR)/$(VALGRIND_SOURCE)