Makefile: Use ${LLVM_PROJECTDIR} during copy phase

Author: Matthew Mets

GNUmakefile

@@ -1178,8 +1178,8 @@ endif
 	@cp -rp lib/wasi-libc/libc-top-half/musl/src/unistd             build/release/tinygo/lib/wasi-libc/libc-top-half/musl/src
 	@cp -rp lib/wasi-libc/libc-top-half/sources                     build/release/tinygo/lib/wasi-libc/libc-top-half
 	@cp -rp lib/wasi-cli/wit                                        build/release/tinygo/lib/wasi-cli/wit
-	@cp -rp llvm-project/compiler-rt/lib/builtins build/release/tinygo/lib/compiler-rt-builtins
-	@cp -rp llvm-project/compiler-rt/LICENSE.TXT  build/release/tinygo/lib/compiler-rt-builtins
+	@cp -rp ${LLVM_PROJECTDIR}/compiler-rt/lib/builtins build/release/tinygo/lib/compiler-rt-builtins
+	@cp -rp ${LLVM_PROJECTDIR}/compiler-rt/LICENSE.TXT  build/release/tinygo/lib/compiler-rt-builtins
 	@cp -rp src                          build/release/tinygo/src
 	@cp -rp targets                      build/release/tinygo/targets