scripts: temporarily pull cheriot-llvm from my GH v17 merge branch

Bypass-Presubmit-Reason: no CI tests; used to successfully update the prebuilt toolchain

Change-Id: I71bcc2d53f03c308d34b2df6ed40b9ce1137a363

download-toolchain.sh

diff --git a/download-toolchain.sh b/download-toolchain.sh
index f397d12..4ad48fa 100755
--- a/download-toolchain.sh
+++ b/download-toolchain.sh
@@ -40,8 +40,10 @@
 TOOLCHAIN_GCC_URL="https://github.com/riscv/riscv-gnu-toolchain"
 TOOLCHAINLLVM_BINUTILS_URL="git://sourceware.org/git/binutils-gdb.git"
 
-TOOLCHAIN_CHERIOT_TAG=
-TOOLCHAIN_CHERIOT_URL="https://github.com/CHERIoT-Platform/llvm-project"
+#TOOLCHAIN_CHERIOT_TAG=
+#TOOLCHAIN_CHERIOT_URL="https://github.com/CHERIoT-Platform/llvm-project"
+TOOLCHAIN_CHERIOT_URL="https://github.com/sleffler/llvm-project"
+TOOLCHAIN_CHERIOT_TAG="cheriot-merge-cleanup-1"
 TOOLCHAIN_CHERIOT_SRC="${TOOLCHAIN_SRC}/cheriot-llvm-project"
 
 if [[ ! "${TOOLCHAIN_TARGET}" == "GCC" ]] &&