kernel: Use prebuilt binaries

perl, lz4c, and a bunch of other binaries are not allowed anymore.
So we need to provide our own.

Change-Id: Idbc88b76247b3dda7c5d52e5eed2d548c33f6f2d
diff --git a/config/BoardConfigSoong.mk b/config/BoardConfigSoong.mk
index 1320c4a..a724a69 100644
--- a/config/BoardConfigSoong.mk
+++ b/config/BoardConfigSoong.mk
@@ -1,9 +1,12 @@
+PATH_OVERRIDE_SOONG := $(shell echo $(TOOLS_PATH_OVERRIDE) | sed -e 's|$$|$$$$|g')
+
 # Add variables that we wish to make available to soong here.
 EXPORT_TO_SOONG := \
     KERNEL_ARCH \
     KERNEL_CROSS_COMPILE \
     KERNEL_MAKE_CMD \
     KERNEL_MAKE_FLAGS \
+    PATH_OVERRIDE_SOONG \
     TARGET_KERNEL_CONFIG \
     TARGET_KERNEL_SOURCE