set rpath for prepare_builtins build utility to find correct stage2
libs at runtime when executed as part of a build
Index: llvm-toolchain-21_21.1.0~++20250728085727+b00e0d2a7e21/libclc/CMakeLists.txt
===================================================================
--- llvm-toolchain-21_21.1.0~++20250728085727+b00e0d2a7e21.orig/libclc/CMakeLists.txt
+++ llvm-toolchain-21_21.1.0~++20250728085727+b00e0d2a7e21/libclc/CMakeLists.txt
@@ -190,6 +190,10 @@ target_compile_definitions( prepare_buil
 # These were not properly reported in early LLVM and we don't need them
 target_compile_options( prepare_builtins PRIVATE -fno-rtti -fno-exceptions )
 
+set_target_properties( prepare_builtins
+                       PROPERTIES INSTALL_RPATH "${LLVM_LIBDIR}"
+                       BUILD_WITH_INSTALL_RPATH "ON")
+
 # Setup arch devices
 set( r600--_devices cedar cypress barts cayman )
 set( amdgcn--_devices tahiti )