[clang/CMake] Respect LLVM_TOOLS_INSTALL_DIR

[loladiro]

Summary

Otherwise clang installs all of its tools into bin/ while
LLVM installs its tools into (LLVM_TOOLS_INSTALL_DIR).
I could swear this used to work (and in fact the julia build system
assumes it), but I can't pin down a specific commit that would
have broken this, and julia has been relying on pre-compiled binaries
for a while now (that don't use this setting), so it may have been
broken for quite a while.

[mgorny]

Well, I've tested it and it doesn't seem to break anything for us (Gentoo) but I don't really understand why you'd have a different install dir for LLVM and Clang.

[vchuravy]

Well, I've tested it and it doesn't seem to break anything for us (Gentoo) but I don't really understand why you'd have a different install dir for LLVM and Clang.

We (Julia) ship LLVM as a dependency and put all the LLVM binaries into a separate tools folder so that folks can just add /bin to their path and don't pick up our custom LLVM.

clang/cmake/modules/AddClang.cmake

if (CLANG_BUILD_TOOLS)
     if(${name} IN_LIST LLVM_DISTRIBUTION_COMPONENTS OR
         NOT LLVM_DISTRIBUTION_COMPONENTS)
       set(export_to_clangtargets EXPORT ClangTargets)
       set_property(GLOBAL PROPERTY CLANG_HAS_EXPORTS True)
     endif()
 
     install(TARGETS ${name}
       ${export_to_clangtargets}
-      RUNTIME DESTINATION bin
+      RUNTIME DESTINATION ${LLVM_TOOLS_INSTALL_DIR}
       COMPONENT ${name})
 
     if(NOT LLVM_ENABLE_IDE)
       add_llvm_install_targets(install-${name}
                                DEPENDS ${name}
                                COMPONENT ${name})
     endif()
     set_property(GLOBAL APPEND PROPERTY CLANG_EXPORTS ${name})