Use prebuilt dir variable for BISON_PKGDATADIR, instead of an absolute path.

Test: m

Signed-off-by: Jingwen Chen <jingwen@google.com>
Change-Id: I329d8f685f60fd05727b65aecb82eb03807e9201
diff --git a/core/config.mk b/core/config.mk
index f086a9a..952656e 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -579,7 +579,7 @@
 # prebuilts/build-tools/common/bison.
 # To run bison from elsewhere you need to set up enviromental variable
 # BISON_PKGDATADIR.
-BISON_PKGDATADIR := $(PWD)/prebuilts/build-tools/common/bison
+BISON_PKGDATADIR := $(prebuilt_build_tools)/common/bison
 BISON := $(prebuilt_build_tools_bin_noasan)/bison
 YACC := $(BISON) -d
 BISON_DATA := $(wildcard $(BISON_PKGDATADIR)/* $(BISON_PKGDATADIR)/*/*)