envsetup.sh: Export LLVM_AOSP_PREBUILTS_VERSION with the current clang version from soong

Needed for KERNEL_CLANG_VERSION if TARGET_KERNEL_CLANG_VERSION hasn't been set by the device config

It's boring to change it on each Google change ...

Change-Id: I1d682611cbf6c60d7ae6227b0b5afde591adf471
Signed-off-by: Jackeagle <jackeagle102@gmail.com>
diff --git a/build/envsetup.sh b/build/envsetup.sh
index 8a815ad..0be41f3 100644
--- a/build/envsetup.sh
+++ b/build/envsetup.sh
@@ -1,3 +1,6 @@
+CLANG_VERSION=$(build/soong/scripts/get_clang_version.py)
+export LLVM_AOSP_PREBUILTS_VERSION="${CLANG_VERSION}"
+
 function breakfast()
 {
     target=$1
diff --git a/config/BoardConfigKernel.mk b/config/BoardConfigKernel.mk
index e01cc49..efe22b5 100644
--- a/config/BoardConfigKernel.mk
+++ b/config/BoardConfigKernel.mk
@@ -92,7 +92,7 @@
     KERNEL_CLANG_VERSION := clang-$(TARGET_KERNEL_CLANG_VERSION)
 else
     # Use the default version of clang if TARGET_KERNEL_CLANG_VERSION hasn't been set by the device config
-    KERNEL_CLANG_VERSION := clang-r522817
+    KERNEL_CLANG_VERSION := $(LLVM_AOSP_PREBUILTS_VERSION)
 endif
 TARGET_KERNEL_CLANG_PATH ?= $(BUILD_TOP)/prebuilts/clang/host/$(HOST_PREBUILT_TAG)/$(KERNEL_CLANG_VERSION)