Use new flex binary

# ---------------------------------------------------------------

# Generic tools.

LEX := prebuilts/misc/$(BUILD_OS)-$(HOST_PREBUILT_ARCH)/flex/flex-2.5.39

LEX := $(prebuilt_build_tools_bin)/flex

# The default PKGDATADIR built in the prebuilt bison is a relative path

# 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 := prebuilts/build-tools/$(BUILD_OS)-$(HOST_PREBUILT_ARCH)/bin/bison

BISON := $(prebuilt_build_tools_bin)/bison

YACC := $(BISON) -d

BISON_DATA := $(wildcard $(BISON_PKGDATADIR)/* $(BISON_PKGDATADIR)/*/*)