CHERIoT: enable using either v13 or v17 toolchain

Bypass-Presubmit-Reason: tested together with other cl's

Change-Id: I685318f770785899373617d2b9791b32a2782de4

toolchains/cheri_llvm/BUILD.bazel

diff --git a/toolchains/cheri_llvm/BUILD.bazel b/toolchains/cheri_llvm/BUILD.bazel
index 45d5c69..2953718 100644
--- a/toolchains/cheri_llvm/BUILD.bazel
+++ b/toolchains/cheri_llvm/BUILD.bazel
@@ -4,6 +4,7 @@
 package(default_visibility = ["//visibility:public"])
 
 SYSTEM_INCLUDE_PATHS = [
+    "external/cheriot-llvm/lib/clang/17.0.0/include",
     "external/cheriot-llvm/lib/clang/13.0.0/include",
     "external/cheriot-llvm/riscv32-unknown-elf/include",
 ]