TF-M: Adds LLVM Clang toolchain

LLVM Clang v18.1.3 added to jammy-amd64-tf-m-build

Change-Id: I8b9fac52979dd5917fd4b4454fe892e411acdd71
Signed-off-by: Matthew Dalzell <matthew.dalzell@arm.com>
diff --git a/jammy-amd64-tf-m-build/tf-environment.install b/jammy-amd64-tf-m-build/tf-environment.install
index afe5244..d6d268f 100755
--- a/jammy-amd64-tf-m-build/tf-environment.install
+++ b/jammy-amd64-tf-m-build/tf-environment.install
@@ -10,3 +10,4 @@
 env | grep PATH >> /etc/environment
 env | grep GCC_7_3_1_PATH >> /etc/environment
 env | grep GCC_10_3_PATH >> /etc/environment
+env | grep CLANG_18_1_3_PATH >> /etc/environment
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