run test with some knowledge of ARCH

scripts/test/Makefile

@@ -0,0 +1,7 @@
+include .config
+
+
+ARCH:	
+	@echo	$(strip $(subst ",,$(BR2_ARCH)))
+#")))
+

scripts/testheader.inc

@@ -1,3 +1,5 @@
+ARCH=`make -f scripts/test/Makefile ARCH`
+
 function mk()
 {
 	scripts/mkpkg $1 $2 "$3"