llvm: fix reproducibility

(From OE-Core rev: a467c0a03d077861c37e317dcb2905b6388cb64c)

Signed-off-by: Alexander Kanavin <alex.kanavin@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/llvm/llvm_git.bb

@@ -99,6 +99,11 @@ do_configure_prepend() {
 	sed -ri "s#lib/${LLVM_DIR}#${baselib}/${LLVM_DIR}#g" ${S}/tools/llvm-config/llvm-config.cpp
 }
 
+# patch out build host paths for reproducibility
+do_compile_prepend_class-target() {
+        sed -i -e "s,${WORKDIR},,g" ${B}/tools/llvm-config/BuildVariables.inc
+}
+
 do_compile() {
 	ninja -v ${PARALLEL_MAKE}
 }