Fix the win_sdk build.

Change-Id: Ia6a300dcee084d79960aba4fba552dd7fd9c2dee
diff --git a/core/config.mk b/core/config.mk
index 5ff8ccf..1be3be0 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -281,7 +281,7 @@
 # To run bison from elsewhere you need to set up enviromental variable
 # BISON_PKGDATADIR.
 BISON_PKGDATADIR := $(PWD)/external/bison/data
-BISON := prebuilts/misc/$(HOST_PREBUILT_TAG)/bison/bison
+BISON := prebuilts/misc/$(BUILD_OS)-$(BUILD_ARCH)/bison/bison
 YACC := $(BISON) -d
 
 DOXYGEN:= doxygen